why are my stock messaging apps different colors on s9 plus and note 8

[Android Central Question]

I have 2 phones the galaxy s9 plus and the note 8 on the note 8 my messaging app is orange but on the s9 plus it is blue. shouldn't they be the same color both are up to date running 8.0 oreo was just curious on which is best and how I could change whichever one isnt as good? also curious as to the differences as to which is better and why? the note 8 is orange with the 4.4 version whereas the blue one Is 5.0. I do see differences when I click on settings but looks more to me they just rearranged and or took away some features. just confused as all figured they would both have same messenger.