User roles on locale sites are similar to pre-defined WordPress roles. On locale sites some additional capabilities are added to Editor role and an additional Translation Editor role is available. Translation Editor it’s a complementary role that can be assigned to Editors, Authors, Contributors and/or Subscribers.
Locale forums are running on bbPress and have a different set of roles and capabilities.
A General Translation Editor (often referred to as GTE) is a person, who has global access to validate strings on all projects for a specific locale. GeneralTranslation Editors are appointed by other General Translation Editors for the same locale. If there are no active General Translation Editors for the locale, a general translation editor can be appointed by a Polyglots lead after a request on make.wordpress.org/polyglots.
A Project Translation Editor is a person, who has access to validate strings on a specific project (for example BuddyPress, WooCommerce or Twenty Fourteen) for one specific locale. A Project Translation Editor can approve strings that are added by translation contributors. Project translation editors are appointed by a General Translation Editor after a request by the project author or by the contributors themselves.
Translation Contributors (also contributors, translators) are the volunteers that translate projects into their language. Translation contributors can suggest translations that need to be verified by a General Translation Editor or a Project Translation Editor