Deciding on a replacement 2 Ton Heat Pump system & trying to make sense of the #'s.

In the Heritage 20's want to know difference between 4A7Z0024 and the 4A6Z0024?

Benefit over a Heritage 16 model 4A5H6024A?

For the Air Handler I'm thinking 4TEE3D31 which would allow me to add the AccuClean later if I choose?

thanks,

Location Dallas