Not mentioned is iReal Pro is a smartphone app that uses the the default midi patches of the smartphone to create the sounds you hear.
As others have mentioned, Band-in-a-Box has the flexibility to playback midi patches that sound more realistic than the default patches available in smartphones or operating systems. PG Music calls their custom midi patches Hi-Q patches. Band-in-a-Box can also use other, third party patches.
So if you stick with midi, you'll hear more realistic sounds than you'll hear from a smartphone.

Band-in-a-Box also accepts audio loops, audio files and can use special audio files created by session musicians called RealTracks. You can't get more realistic than audio files.

All play whatever chord sheet you create.

I forgot to mention Band-in-a-Box only runs on Windows or MacOS computers.

Jim Fogle - 2025 BiaB (Build 1128) RB (Build 5) - Ultra+ PAK
DAWs: Cakewalk Sonar - Standalone: Zoom MRS-8
Laptop: i3 Win 10, 8GB ram 500GB HDD
Desktop: i7 Win 11, 12GB ram 256GB SSD, 4 TB HDD
Music at: https://fogle622.wix.com/fogle622-audio-home