How to tell my kid her friends probably aren’t her friends?

So my child is a social butterfly she’s very outgoing, very loud, very open minded, and very verbal when she’s at home. When we go out depending on where like church or school she’s very open minded, outgoing still but not verbal or anything. The problem comes in that she has a friend problem. She’s a follower she likes to follow other kids and call them her friend after they play with her once or twice. I tried telling her that those aren’t friends but she’s 4 so it goes in one ear out the other. For example at church this Sunday she was running around cuz this little boy was I had no problem with that. This lil boy was someone she was following and trying to be friends with since she was 2 so I’m okay with that. But this morning when I was dropping her off she saw a “friend” and wanted to walk with her. I try to tell her she can’t and pull her away because she can be aggressive when it comes to that. So her “friend” said hi first then she turned around and lit up like a dog about to get a treat. She walked with her but her “friend” didn’t want to talk to her or walk with her. She wanted to hold her “friends” hand and she swat it away. I told her not to touch people without asking them first. And well she tried again because they’re in the same class. But the little girl looked to be disgusted or annoyed with my kid. Idk maybe I’m overreacting but this isn’t the first incident like this. How do I talk to my daughter about friends and what they’re like for someone her age to understand.