They basically mean alsmot the same, but when to use could vary.
I would not say there are noticeable differences between those words, whereas you will get used to using it by reading at different ways of use. 선택 and 택 can be used to express same sentence. For instance..
도망갈바에는 싸움을 택하겠어
도망갈바에는 싸움을 선택하겠어 - both of them could express the same meaning.
In contrast, if you try to say with 고르다, it may sound a bit awkward.
As the other person already mentioned, they are more often used in a situation selecting something within small choices. It is ,however, not necessarily alwaus right. Here i will give you some examples,
이중에 무엇을 선택할래요?
이중에 무엇을 택할래요?
이중에 무엇을 고르실래요? - What would you choose among those?
All of them sounds very natural.
Furthermore, 선택 is generally used as a noun. If you like wathcing korean dramas or films you may have heard of it sometimes.
그것은 너의 선택에 달려있어- That is up to your choice
What it can also means is that " That will depend on your decision.
Accordingly, i guess you can understand that this could imply decision.
These are all i can help you with. I am sorry if it confuses you more haha..
한국어 공부 열심히 사셔서 보기 좋습니다^^
화이팅