Complex sentence: Ruby's powers manifest as heat and fire, and she is hot-tempered and irritable, while Sapphire can freeze her surroundings, and stays relaxed and perpective.
Split into simpler sentences: Ruby's powers manifest as heat and fire, while Sapphire's can freeze her surroundings. They also have differing personalities; while Ruby is hot-tempered and irritable, Sapphire stays relaxed and perpective.