I don’t think there’s a lot of difference other than - I find a Syrian easier than a Robo because a Syrian will use a litter tray so less need to clean out so often and if you have a good depth of bedding you can spot clean for quite some time and not need to change the substrate for 6 to 8 weeks. Which is also better for the hamster as cage cleans stress them. So partial cleans are better - eg doing things at different times as and when needed so something always smells familiar.
The more substrate you have in the less you use in the long run
. I haven’t had a Russian dwarf hamster but believe, like robos, it is difficult to know where they pee so makes spot cleaning a bit more challenging.
Syrians are generally a bit easier to handle and tame than a dwarf hamster, for a new owner, although their houses/wheels are larger than those of dwarf hamsters so that needs bearing in mind when thinking about the type of cage.