What is the main difference between bcprov and bc-fips (bouncycastle) jar?

What is the main difference between bcprov and bc-fips (bouncycastle) jar?

I am having difficulty understanding the differences between bc-prov and bc-fips jar. I understand bc-fips contains the subset of bc-prov packages as well. But I want to understand more about the below questions,

1. Will there be any performance impact upgrading to bc-fips jar provided I still use the same algorithm, key length, iv length, block modes, etc.?? This is a key factor in upgrading to the bc-fips jar.
2. Is running bc-fips in non-approved mode equivalent to using bc-prov jar? I mean, in terms of the functionals APIs coverage, performance, backward compatibility, etc.?
3. Why can bc-prov and bc-fips not co-exist together? Because of this, it will be hard for legacy apps to migrate to bc-fips for FIPS compliance easily.
4. Is there any upgrade guide for migrating to bc-fips from bc-prov for legacy applications?