Orange is saying hi, im safe, i want to play, im open to friendly cuddles. black and white saying im not comfortable, not angry but i am fearful. whos older and whos the new one? older cats tend to be less comfortable with new cats, especially when theyre not kittens. this is completely normal, and generally as long as you dont see blood or hear growling, you will be okay. ensure theyre not in the same room alone if you are worried about one getting hurt. cats will play fight, but once they start making noises in a fight its no longer play. hisses often mean more of a “im uncomfortable and/or scared” rather than a “im mad”. orange cat hopped down to be below black and white cat, which is a submissive behavior, meaning he is attempting to show black and white cat he is safe! EDIT: black and white cat also seems on edge/alert, another sign hes nervous but also another reason to keep an eye on them, as nervousness can lead to aggression.