I'd prefer to go to the park.

[B45]

What's the different between:

I'd prefer to go to the park.

VS

I prefer to go to the park.

Is one more polite than the other?

 

[Raymott]

Yes, "I'd" uses the polite 'would' form. It means something like "I would prefer to go to the park if that's OK with you / if you don't mind / unless you really want to go somewhere else."
"I prefer to go to the park" makes no concession to the other person. It doesn't take their wishes into account.

 

[Tdol]

Is one more polite than the other?

It depends- are the speakers deciding where to go or simply discussing the kinds of activities they like?

 

[B45]

It depends- are the speakers deciding where to go or simply discussing the kinds of activities they like?

Discussing the activities they like.

 

[Tdol]

In that case, I'd use the second.