Photo above does not look like any military uniform..
On the photo below there is a tzarist army cossack cavalryman pictured (rank is private)..
I second that opinion. First one appears to be a civilian. Not any regulation uniform, merely military in style, with no insignia of any kind. Wearing those kind of riding breeches makes one think this fellow has some pretentions to status. Appears to be a social class or two above the cavalry soldier.
"War is an ugly thing, but not the ugliest of things. A man who has nothing for which he is willing to fight, nothing he cares more about than his own personal safety, is a miserable creature with no chance of being free unless made and kept so by the exertions of better men than himself."
First photo is not unlike many chauffeur photos from the turn of the century. NH