For example, I'm comparing
an ASRock X470 Taichi to an ASRock Fatal1ty B450 Gaming K4.
The X470 has 8 SATA (6 chipset, 2 third-party) while the B450 has only 6 SATA (4 chipset, 2 third-party).
The X470 has 8 USB (six 3.1 Gen1, one 3.1 Gen2 Type-C, one 3.1 Gen2 Type-A) while the B450 also has 8 USB but they're of older standards (two of the 3.1 Gen1 are replaced with 2.0).
I also notice the X470 has Wifi, more temperature sensors, and a slightly better integrated soundcard.
So basically, the X470 just has a few more bells and whistles.
So if money is tight, the B450 will do you just fine. If those $200 are critical, I'd say you're better off getting the B450 and putting the $200 into a bigger SSD or a better graphics card.