Differences between CollectFragmentCounts and CalculateTargetCoverage

Good afternoon,

I was hoping somebody could help illuminate the differences/similarities between CollectFragmentCounts (4.0 official release) and CalculateTargetCoverage (4.3 Beta). Are these the same tools / are they using same algorithm?

Also, is the Picard-style header produced in CollectFragmentCounts necessary for downstream tools now?

Thank you so much!