Arranger keyboards are characterized by their automatic accompaniment styles, which are essentially multi-part MIDI riffs that follow your chord changes, adding not just a drum beat but several virtual musicians worth of backing band as well. Their feature sets and price points range from basic accompaniment and easy-play features found on some $149 Costco impulse purchase to the $6,000-plus Yamaha Genos, a songwriting and performance monster machine that can basically sound like anything and do anything. Arrangers are also some of the most maligned and least understood keyboards among many pros.

https://www.pro-tools-expert.com/synth-expert/news-blog/2017/10/6/why-arranger-keyboards-matter