Shuten/shushaku etc

When travelling in Japan by train I noticed they say shuten at the final station. However when going to Hokkaido and using trains they say what sounds like "shushaku" instead. What does this mean and why the difference?

It is just slight variations of saying the same. It is similar to "last station" vs. "final station" in English, etc. Different regional companies are following slightly different conventions.

Another example is doa (Kanto) vs. tobira (Kansai) for train door related announcements (I think).

It probably was "shuchaku" or "shuchaku eki" ("eki" meaning "station").

"Shuten" is (literally) "end point," and "shuchaku (eki)
" is "terminating station," or "terminal."

I checked a question forum (in Japanese) about the difference, and noone seems to know the answer :)

Maybe it is a region oriented way of saying it, as you said.

It was just such a sudden difference as I flew from Fukuoka to Sapporo, the train announcement said "shuchaku". Of course everything is a bit different from southern Japan, nature, climate, etc so I guess it makes some sense :)