Unlike the relatively straight-forward structures of the nobility and Church, the guilds of the League of Merchants are a sometimes confused combination of labor union, corporation and trade association - and guilders, too, vary in their general purpose between laborer, industrialist and bureaucrat.
The Guild as Labor Union
The lowest-ranking guilders are labor - the 'labor' workers and chiefs, the apprentices and journeymen, even some guild managers are salarymen and wage-workers, employed either by noble or Churchmen or by higher-ranking members of their guild.
To use the Reeves - in some ways the prototypical guild - a Reeve clerk named Toby Tam might be employed by a nobleman to aid his steward, the local Cathedral to count tithes, or as a law clerk in the Reeve firm of Williams, Shrum and Meeks. In all cases, he receives his wages and is principally concerned with the wishes of his employer, and his relationship to the Guild is that of a worker to a labor union. If his employer mistreats him, he'll turn to the Guild for help, who will lobby his employer for better wages or conditions. Indeed, Tam's basic rates are fixed by the guild to keep prices up, and the guild also serves as a hiring hall to aid Tam in finding work should he prove unemployed. The guild additionally may help if Tam is injured or ill, and generally provides a sort of community safety net for Tobias Tam. In turn, Toby pays the guild dues, and also is beholden to the guild in political matters; the guild may ask Tam to stay home from work in the case of a dispute with his employer, or to slow down work or otherwise engage in activism.
Toby is not, however, paid by the guild - he is paid by his employer, and the degree to which the guild leadership controls him is based upon Toby's desire for promotion (controlled by the guild) and whether he believes he will need to rely on the guild soon to find him a job or exercise political muscle. Consequently, ambitious guilders or those in transient or mistreated jobs are quite beholden to guild leadership, while workers with fair employers who pay high wages can largely ignore the guild in favor of the person who signs their paycheck.
The Guild as Trade Association
Mid-ranking guilders - mostly managers and directors, though sometimes journeymen or executive directors - are largely businessmen, running a business that provides some service to clients in the nobility, the Church, the free populace or the rest of the League. Some high-ranking guilders might be independent contractors, effectively operating as above as laborers, but mostly, the managers and directors control firms. These business might be law offices among the Reeves (Williams, Shrum and Meeks), military companies among the Muster (the Bulldogs), single-starship trading firms among the Charioteers, factories or repair outfits among the Engineers or casinos, brothels, pawn shops or exploration companies among the Scravers.
Sometimes, the largest of these corporate-style organizations are Known Worlds-wide; the Scraver families, for instance, each operate importantly as a company beneath the family's uncle and aunt, and the hongs represent interstellar shipping firms owning fleets of merchant ships. In all cases, however, the relationship of the individual business to the guild is similar to the relationship of a company to a modern trade association - particularly the sort of association that certifies its members. Businesses rely upon the guild and guild leaders to facilitate contracts and protect them against the predations of the Church and nobility, to mediate disputes between businesses and lobby for their collective interests in the halls of power. In turn, the guild receives a cut of a business' income and expects political support in times of embargo or slowdown as well general backing when push comes to shove.
Unlike the 'labor' elements of the guild, where the guild gives in many ways more than it takes, business owners often feel as if the guild takes more than it gives the larger they get. While small merchants rely upon the guild to provide political muscle, the largest businesses - particularly when they reach a planetary or inter-planetary scale - often feel as if guild rules restrict them in favor of their guilder employees or their smaller competitors. Of course, at the highest levels, it is the major corporations - the hongs, the families and the like - that control the guilds, so in the gamut of businesses guild control ranges from high over the smallest of business, low over medium-sized businesses, and high again over the largest businesses as they are often those setting guild-wide policy.
The Guild as Political Organization
Many of the highest-ranking guilders - vice consuls, consuls and deans - work for the guild directly rather than running some business of their own, or do so in addition to running their own business. Especially in the Charioteers and Scravers, the latter is particularly common, as the hongs and families largely control the guild and divvy up its official functions among themselves as prizes. Some lower-ranking guilders serve as assistants to true guild officials as well, but the guild is always careful to make sure that its official functions are handled by someone who works for them.
We'll take as our example a guild consul, who may serve as the planetary or regional representative of a guild as a whole. The consul and his staff serve the functions mentioned above - aiding individual guilders or guild businesses in trouble, collecting dues, and serving as a hiring hall - and in addition, the consul represents his guild and its interests as a sort of ambassador to the other major powers of a world. Certain functions also fall to the guild itself to manage; agora contracts are taken by a guild rather than by an individual company (though in-guild factions such as hongs may vie over that control), as are contracts to run and maintain planetary institutions like starports (always a Charioteer affair) and terraforming engines (the Engineers). As a practical matter, much of the functioning of agoras and other planetary institutions are then subcontracted to individual guild businesses, but those contracts and their disbursement is handled by the consul or dean of a particular region or world.
Finally, official guild leadership controls all promotion to rank of master/manager and above, and while they listen carefully to the advice of business owners wishing a formal increase in rank for one of their employees it is the consul's call. Deserving journeymen can languish for years before their mastery because they've earned the consul's ire, and guilders seeking the rank of director or executive director need to actively curry favor from the local leadership - and if they lose that favor, a vice consul or consul could easily be busted back to director or even manager by the dean.