I read about tick / tech throws on Street Fighter sites. What is this? Are there differences between the terms I mentioned or do they refer to the same thing?
A tap (tick/tic) throw is one where you repeated jab at your opponent, forcing them to go into blocking motion often, and then surprising them with a throw attempt. This is one of the best ways of pulling off a throw against an unprepared opponent. You can mix this up to great success if you do it right. For example, if your first high kick (gets blocked) -> throw is successful, next time you try it, your opponent might anticipate it. Instead, you can do high kick -> low kick instead. If he tries to anticipate your throw this time, you get in a free low kick which can lead into a combo.
Tech throwing is what you can do to counter a throw attempt by an opponent. As the throw motion starts, you have a few frames of reaction time to attempt to prevent the throw (called a technical) by performing a specific action.
This video demonstrates that as well as some advanced plinking techniques: