In addition to the fact that there are different varieties as people have noted, plants change as they age. A nice, new seedling will sometimes be softer, and gradually get more woody as time goes on.

I've seen this with rosemary and with thyme.

There are different types of rosemary, and as the other poster said there are differences within one sub-species that can make identification a hazy academic pursuit.

If you bought rosemary that was labeled as such, you know you have rosemary. The plant you took out, consider it a type of rosemary and leave it at that. If you like the rosemary you had better, you can clone it with a cutting and grow it anew.

There are quite a few (at least 20, probably more) varieties of rosemary. It's a wonderful herb, and I should try growing it again. I keep killing mine, so maybe I should give up. Nah!

https://www.embracegardening.com/different-types-of-rosemary-plant-varieties/

https://housegrail.com/different-types-of-rosemary-plants/

https://herbgardencooking.com/rosemary/

Culinary herbs like rosemary have tons of varieties. This is likely the reason but they should both be fine to eat.

The number of different basil varieties / cultivars in Culinary Basil (Ocimum basilicum) is mind blowing. That isn't even counting the different species of basil such as holy basil (Ocimum tenuiflorum).

Could one possibly be lavender? They’re actually quite closely related and the smells aren’t entirely different either.

When we bought our house there was one of each in the garden right next to each other and it took us a while to figure out what was going on.

Lots of plants have different varieties of the same species. It's impossible to say without knowing which variety. It should be stated and described on the tag from the grower.