Learn English – To “call” vs “name” an unknown thing

I can't think of many terms for this... all I can think of is a crossing or railroad crossing (Merriam Webster).

As for the "red-white" thing I would call it a gate or railway/railroad crossing gate - very descriptive terms, but that is what I would use.

As for your sentence I would say "At the railroad crossing, when the gates finally lowered, it was obvious I would be late for the party".

Check out the "Rail crossing warning signs" from Wisconsin, there might be other resources from other parts of the English speaking world?

AFAIK, barrier is more common in British English for the "gates" talked about above. Australian English i have heard of booms - but about these two I'm not the one who should be asked ;-)

Surely there should be more of a difference between the two words. If they mean the same thing surely there would be no need anymore for two words

There are a lot of near synonyms in English, so this does not follow at all. It's particularly so when you consider that act entered the English language in the late Middle English period, from French, while deed was in the language from the very beginnings of Old English. Many, but not all, seeming redundancies in English vocabulary have a similar origin story.

It is true that there are differences in nuances. The primary one would be that an act would generally be need to be relatively remarkable before we would use the term deed. One can do a particularly brave or noble or dastardly or evil deed, but one can't really do a lazy or everyday or common deed. There's nothing technically wrong with the latter, but it wouldn't be an idiomatic use.

There are similarly some differences in what verbs and prepositions are used with either. One doesn't do an act, one cannot be in the deed of anything.