When you are building a home, and the floor plan states that floor joists will span a certain length and they end up being anywhere from 2-7" difference, Is that a big deal? How strict are building codes with floor plans?

It depends on the inspector.

We have an inspector that does not know what a bearing wall is and can not read prints.
She is scary.

Chuck

When you are building a home, and the floor plan states that floor joists will span a certain length and they end up being anywhere from 2-7" difference, Is that a big deal? How strict are building codes with floor plans?

2 inches to 7 inches is not a big deal. 2 feet to 7 feet difference might be.