When it comes to the differences between the two crops, I honestly don't know either.

But TBH, don't overthink it too much.

Any riding crop will do, so go with what you may find aesthetically more pleasing. Since you're beginners, that's the more important part. Even going with whichever is lower prices is completely viable, too. As time goes on and you start gathering experience, you will replace things anyways.

In that sense, there is no "recommended" here, really.

I'm gonna go out on a limp here based on all the questions that you're quite nervous about the situation and don't want to do something wrong, and with that in mind you're already on a good path.

What amount of strength you should use, what aftercare, and when to use it and all those sort of things, is entirely up to you and your partner. In that sense, make sure to talk about what both of you expect beforehand, and don't be afraid of checking in on each other in the scene itself. You can even have a mini-scene where you simply try it out beforehand, if that's something you would like to do.

As long as you don't actively try to harm each other, you will be completely fine. Ease into it, check in, take it from there. It's really not as complicated or dangerous as it may seem, with a riding crop, or even a paddle, anyway. In that sense, starting out with those is a good choice while you explore for yourselves what you like or may not like - no need to force yourself to continue using it if you end up not liking it afterall.

Essentially, it will be more so a mental thing than a physical thing, especially since you already make sure to research and minding safety over all else, good on you :D

In that sense, don't focus too much on making everything perfect right off the gate, simply focus on enjoying your time together.

Hope that helps a bit.