1. Clapper wasn't investigated for lying under oath to Congress, and the clock recently run out via statute of limitations a few days ago. Entirely Sessions' Decision.
2. Comey demonstrably gave classified info to his law professor buddy to leak, to start this whole Mueller SC investigation. It's a slam dunk case. Congress critters referred him to DOJ for prosecution. He's running around selling books, tweaking Trump's nose. Why hasn't he been arrested for it?
Because that's how it works. As you may have noticed, Hilary got a really sweet book deal too. McCabe was too minor to rate a book deal, so instead he got a go-fund-me to help him trash Trump. If he does a good job trashing Trump he might get a book deal too.