Playing or fighting? *New kitten*?

I just got a new kitten today. He is 2 months old and neutered. I also have a 5 month old female kitten (spayed) who, up until a few weeks ago, had another cat companion-they got along great.
The older cat will pounce on the newbie, swat (claws retracted) and bite at his body and then proceed to groom him. She alternates this and sometimes the newbie is ok with it and purrs and other times he hisses at her and backs away.
Right now they are sleeping practically next to each other and seem content.
I tried to keep them separated at first but after my older cat got into the room all ninja like and they met face to face, I figured I'd stand back and see what happened.
Is this alternate fighting ok?

Ok, I think they may be alright together...a few minutes ago they were mutually grooming and the newbie was curled up next to the older kitten and was receiving a full body bath with both kittens loudly purring... yay!

Cats establish a social order. Based on the behaviors you're telling me, the older girl is fighting for dominance.. That's all. If she was truly put out, that little one would be hurt or dead by now, not sleeping comfortably and all cleaned up next to the older one. The key point was "(claws retracted)" When this little guy grows up, he'll probably be the dominant one. Make them play nice as much as you can, but don't sweat it until he gets hurt.

When I first got my two cats together, they were like that. Actually they are still like that. They don't hurt each other so I don't worry too much.
Just make sure that they are not hurting each other.

their fighting they will get along in a few weeks the same happened to my cats

I'd keep an eye on them to be sure the little one doesn't get hurt, and I would probably not leave them alone together at this time. Vet bills are expensive and you'd probably feel pretty badly if the baby got injured.

The good news is that cats are naturally social animals and usually manage to work things out without someone getting seriously injured...this is less true of un-altered animals.

The big one is probably just playing, but is so much stronger it can injure the little one, and the little one is letting it know. Hopefully within a couple of weeks they'll be best friends.