The words “decision” and “choice” seem to be pretty much synonymous in English, as do their verbal counterparts “decide” and “choose.”
However, they strike me as having slightly different meanings. It seems to me that you decide whether or not to do something, while, on the assumption that you have decided to do something, you choose between multiple options.
So, if your choice is between acting and not acting, you’re deciding, but if your choice is between two or more distinct acts, you’re choosing. You’ve decided you’re going to act, and now you have to choose which action to take.
This makes it seem like decision is primary (to act or not to act?), while choice is secondary (given the decision to act, which act?) And yet, since we can frame a decision as a choice between two opposed options (one being the negation of the other) — and even in a “normal” choice, each option excludes (is the negation of) the others — maybe choice is the more fundamental.
Or perhaps decision is prior to choice logically (choosing implies that you have decided), while choice is prior to decision ontologically (decision is a species of choice).