Which / What

[jack]

What do these mean?
1. The one you choose should depend on which features you need.
2. The one you choose should depend on what features you need.

[Casiopea]

What do these mean?
1. The one you choose should depend on which features you need.
2. The one you choose should depend on what features you need.

which implies a choice, whereas what implies everything.

What's your favorite colour?
Which is your favourite color, deep blue or sky blue?

In your example 1., the choices to which which refers have already been stated, so the speaker/writer leaves them out.

[jack]

In your example 1., the choices to which which refers have already been stated, so the speaker/writer leaves them out.

Thanks. This is very useful.

the choices to which which refers have already been stated, so the speaker/writer leaves them out.

Are these corrrect?
1. The choices to which which refers have already been stated, so the speaker/writer leaves them out.
2. The choices to which which refers to have already been stated, so the speaker/writer leaves them out. (Is 'to' omitted here?)

3. The chocies to which this refers to have already been stated, so the speaker/writer leaves them out.
4. The chocies to which this refers (omitted) have already been stated, so the speaker/writer leaves them out. (Is 'to' omitted here?)