Some distinctions:
AMP girl - Will typically service anyone that walks in the door that can pay. Degree of service may depend of the level of connection, however. AMP may bar certain people with bad track records. Typically no emotional connections, but may be open to it. No questions.
Escort - Will arrange meetings on demand for $$, but may be selective if you creep her out somehow. Typically no emotional connection, but there are exceptions. No questions.
Sugar Baby - Will arrange meetings on demand for $$, but more exclusive than an escort. You will likely have to audition first before she will see you. Will typically see a small group of approved men. Not as available as an escort. May develop an emotional connection to some men. However, some SBs may function more like escorts. No questions.
Mistress - Heavy emotional connection. Will be exclusive to you. Knows you very well. Understands that you are married and she will always be #2. Financial support may or may not be required.
GF - Mid to heavy emotional connection. Expected to be exclusive (both ways). Knows you well (or thinks she does). Assumes she is #1. Expects affection and tokens there of. Typically, no direct financial support. Provides regular, typically enthusiastic sex, including BBBJs. Aspires to be wife. Disposable.
Wife - Exclusive to you (and expects you to be exclusive to her). Knows you intimately. Assumes she is #1. Heavy financial and emotional support required. May or may not provide sex. If not, see one or more of the above. If she finds out about one of the above, will rip you apart like a wildcat (physically, emotionally, financially).