as far as the engine goes, one thing i like is that the rytm has fm machines, the buss compressor on the end is amazing as well, the velocity sensitive pads are also awesome
you can do drum sounds on the analog4, but it isn’t really geared towards percussion like the rytm is, for an analogy its like yes you can make drum sounds on a roland sh101 but having a purpose built drum machine like a tr909 is useful as well!
in my humble opinion, you need both, use rytm for percussion and some basic mono synth like capabilities, and use the analog 4 for evolving pads and basslines and other synthy goodness