A gravel bike is a bike intended to be capable of gravel.

A gravel bike geometry is the geometry on a gravel bike.

For various reasons, there are a lot of opinions about what a "gravel bike" should be capable of and optimized for. Some people are looking for a a high-performance road bike that happens to fit huge tires and has itsy-bitsy gears available. Some people are looking for simplified mountain bikes. Some people are looking for.... whatever. Lots of things.

Within any goal, there are a lot of different thoughts about how the goal should be reached.

Also, bike categorization can be affected not just by the engineering teams, but also by marketing. For example:
In the wake of the bike boom, everything was drop-bar road bicycles. So the 1983 Miyata 710, a mid-range road bike, was not just "ideal for sports riding", but also "commuting."
But through the early 1980s the mountain bike began to gobble up general-use markets and threaten road bikes. So although the 1984 Miyata 710 was basically the same bike as a 1983 Miyata 710 with a few upgrades and a new paint job, according to the catalog it now featured "TRIATHLON DESIGN." And somehow, it had lost its commuting usefulness.

Categories and definitions are fuzzy guidelines.