“Community was here” vs “Community existed”

Question

What is the difference between the following two:

I didn't know if this community existed

I didn't know if this community was here

Answer 1

The first example is incorrect - you have your tenses mixed up. It should read:

I didn't know if this community existed.

Once that has been corrected, both mean broadly the same thing.

I would, however, have worded them slightly differently:

I didn't know this community existed.

I didn't know this community was here.

After your comments, however, the meaning can be very different:

The king of Spain was here

means that the king was in this place, but

The king of Spain existed

is confirming that there is a king of Spain.

Answer 2

I didn't know if this community existed states that I was completely unaware of the fact that this community existed.

Whereas I didn't know if this community was here states that i was aware of the fact that this community existed, but i did not know that it was here.