Updated Samsung galaxy A5 to Marshmallow but look and feel remains that of Lollipop
Lower-end phones usually won't get the new manufacturer skin (that's on the new flagship phone) with a new Android version.

As for the launcher, bootanimation and stuff, it's how Samsung chose to make it in their TouchWiz skin - they don't necessarily follow how Google do it on Nexus.

Try installing Google Now Launcher if you want the vertical scrolling experience. Not looking as harmonious on top of all the TouchWiz icons but better than nothing.