Why would it be thunder armour with the exact same helmet as MkIV?
And the second one is the Black Templars Crusader Helmet.
http://www.bitsandkits.co.uk/black-templar-crusader-helmet-p-18.html
I cannot see Forge World, who go to great lengths to produce models which fit the background and scale for 40K would go and fuck up something as big as granting Thunder Armour Mk1 Pattern Power Armour the go ahead to look exactly like Mark IV and Mark VII Crusader variant Armour.
Neither would the Thunder Armour have the Imperial Eagle on it, as that symbol was not used until after the Heresy (other than for the Emperors Children). Even the Mark II, Mark III, Mark IV and Mark V follow that pattern - they don't have the Twin Headed Eagle on the chest plate.
No offence guys, but fuck me. That was painful to write.