This sort of thing created a rift in my family that has yet to heal.
DH and I married when my DD from a previous marriage was just over two years old. DH considered her "his" from day one, and treated her as such, even after we had a child together. DH's dad never accepted my DD, and always gifted her differently...meaning far less...than his other grandchildren. When she became old enough to realize this, DH talked with his dad and let him know this was unacceptable. His dad ignored him, and DH cut off contact with his dad. Period. I thought the reaction was too harsh at first, but DH said, "What kind of person would knowingly hurt a child's feelings over and over again?" He had a point.
On the opposite end of the spectrum, there's my mom. My brother and I, both in our 40's, get a kick out of her complete panic when she realizes she's spent more on gifts for one of us than on gifts for the other. Now, there are grandchildren in the mix, and she feels she must spend precisely the same amount on each of them, too! We all tell her it's not necessary to be THAT fair, but she persists. She doesn't want anyone to feel they are less favored!
There is a happy medium somewhere in there, and honestly, I think a lot of people who gift step-kids differently aren't deliberately being mean-spririted. I used to be bad about buying more for my neice than my nephew. I didn't mean to do it...she was just easier to buy for. When someone brought it to my attention, I corrected that behavior...and I explained to Nephew why I'd bought more for his sis in the past. He's a smart cookie. He said, "Yeah, she likes EVERYTHING!"
I wouldn't stop trying to get hubby to understand your viewpoint on this, OP. You're justified in feeling hurt. You obviously try hard to do the right thing, and it's reasonable that you expect he do the same. I hope you're able to resolve this quickly, and have a Happy New Year with your blended family!