will a battery on a 94 ford Taurus work on a 95 Mazda protege?

If the dimension fit, then voltage is not a factor.

By dimensions I do not mean just length and width, but height and ability for cables to reach.

They can also differ based on top posts or side bolts.

They are all 12 volts. If the Mazda needs more amperage than the Ford battery is rated for, you may have issues cranking the car up, especially if the headlights are on, but if you are broke and desperate, it'll get the job done for a little while. If the two cars have similar cold cranking amperage requirements, you may not have any trouble at all.

You have to have a battery with the correct amperage for the car. most cars need 480 amps to crank the engine from cold. Less than that and the battery is not suitable.

If you can get it in there then it is good. Go for it.