Question about 5G PDSCH mapping types


What is the motivation to have two mapping types for PDSCH if their characteristics are almost the same?

I saw that before Rel16 mapping type B was called “mini-slot”, and the allocation included 2,4 or 7 symbols in this type, but now this is not the case (range of 3-14 symbols for type A, and 2-13 for type B).
So i really don’t understand the motivation for two different allocation types now.

If someone could make things clearer for me it will be great.