First off, thanks a lot for this interesting comparison! You are a true Data Junkie 
I thought as both are index-tracking ETFs they would just blindly mirror that index… Only now I realized they track different indexes (iShares = S&P Global Clean Energy Index vs. Invesco = WilderHill New Energy Global Innovation index)!
As for those Hydrogen stocks, especially the ones more focused on Fuel Cells… Dangerous territory. I recommend this Liebreich master piece: https://about.bnef.com/blog/liebreich-separating-hype-from-hydrogen-part-one-the-supply-side/
That said, in comparison I do prefer the Invesco too now.