Jonesy nailed it. I am a boot lover and they are ALL different

They ARE different.

One pair will match cool colors and the other warmer colors. That's a world of difference. If you are into knee high boots and live in a place where the weather justifies it, then I say absolutely keep both pair, as they will be very handy in Fall and Winter outfit building.

( and BTW I don't own that many pairs myself, despite living in Canada).

I like both and think they are different enough to warrant keeping. I don't mind the height with skinnies or a skirt, both work for me. Last year I purchased a pair of the Jane tall cuff in taupe, and I hard a very hard time creating outfits for them. The light color was very different from my other boots (gray and chestnut) but it was TOO different. I needed a darker color. I brought them to a YLF swap and this year picked up a pair of black boots to replace them. I learned I like a range of tall boots, but they all need to be on the darker side for my needs.