Brush versus comb

I have two cats brother and sister. The boy is a smooth fine short hair coated cat. While his sister is just the opposite she has a short coat but it is very thick, she hates the comb, while he loves it. The brush is liked by both two a certain extent. I can not brush where their private parts are, I get a snarl and at times I get bitten, do what do I do. I decided to get this comb, it is a very good idea to get through both coats, as they both get lugs, so I bought it, but even though I am managing to get into places I couldn't get before. I'm still having problems combing their back legs and stomach. I'm so frightened of hurting them but I need to get rid of the lugs, and the soft hair because it is causing myself problems, the hair is getting everywhere. So I'm gently having to coax them to allowing me to comb their parts they can not get to. I wash their blankets every week and they now have their own beds because they fight. So I'm getting on better than I thought the bottom line is I would rather buy and use this Comb as it is easier than any brush, it is not half as bad as these wire brushes, the last one I had not only cut the hair down it cut the cats bodies. Which in its turn hurt my cats they were sore for over a week, now I can comb them but not hurt them, I'm happy and so are my cats.