It's a totally shallow classification. Slower and Faster are relative terms, curious is a relative thing, energy is a relative thing. The problem is that engineers create these generic "boxes", place their staff in it, and divvy out work/rewards/responsibilities based on it. It's just like designing an object oriented framework. Your original classes are probably not quite right.

The problem is your boxes are almost certainly overly generic. You might say Joe is just a slow developer, put him in that box and move on. Maybe you talk to Joe, and he doesn't quite tell you exactly why he's slow... he might not know why. You have to dig deeper into it. Maybe he has weaknesses he is afraid to tell. For example, he might be slow because he has 10 years of doing C++, and now he's on a Node.JS team. All his prior knowledge is nearly obsolete. Maybe he's slow because he's not interested in tech problems, instead he's more interested in learning the domain... so he's just not motivated to work fast. Maybe he's slow because he wants to move up in his career, but there's no clear path where that is possible. Maybe he's slow because he has a new born baby, and he doesn't sleep at night.

If you just put him in a box, you're not going to work to try and find his strengths, and play to them, you're not going to work with him to find solutions. It is YOUR job as manager to learn what makes up your team as individuals, and to help them grow. If you just put him in a "box" you're going to call him weak, and your team will work at a crippled pace.