How are Exchange Type availability searches different from the Exchange Type searches we already have in the Filters?

On your home profile, it's possible to say that your home is generally available for specific exchange types. For example, you could say that you accept simultaneous and non-simultaneous exchanges but not non-reciprocal and hospitality exchanges. It's also possible to add explicit availability while specifying the type of exchange for a date range. The Exchange Type filters on the main search screen work with explicit availability. They don't have to be used with date or Last Minute filters but it makes more sense if they are.