Darce: an arm triangle from the front where your choking arm enters from the side of your opponents enclosed arm. The hand of your choking arm typically anchors in the bicep of your secondary arm, RNC style (although there are other variations). You cut off blood flow on one side of the neck with your forearm and on the other side with the shoulder of your opponent's enclosed arm. Typically entered from top of side control when opponent comes up with an underhook.
Anaconda: the mirror image of the Darce. Your choking arm enters from the side of your opponents neck. You cut off blood flow on one side of the neck with your bicep and on the other side with the shoulder of your opponent's enclosed arm. Typically entered from front headlock position with opponent on all fours.
Both the Darce and Anaconda are best finished with your body perpendicular to your opponents body.
Guillotine: Lot of variations here. It can be executed as a blood choke or as air choke, opponents arm in or arm out. One common factor is that you are parallel with your opponent, chests more or less facing, with your legs pointing more or less the same direction. The finishing mechanics for the arm-in guillotine are different from the Darce or anaconda. You can't really drive their shoulder into their neck, so you have a shallower grip with your wrist on their trachea and crunch your body towards their head, basically folding their throat over your wrist.
Schultz choke: Sort of like the anaconda, except you have a Gable grip instead of the figure-4 RNC grip and you use your head to help drive their shoulder into their neck.
Peruvian necktie: Like a guillotine, except you throw your leg over the back of their head.