border vs butt on

border is a noun but butt on is not a noun.

Word	Noun	Adjective	Verb	Adverb
border	Yes	No	Yes	No
butt on	No	No	Yes	No

As verbs, border and butt on are synonyms defined as:

Other synonyms of border include abut, adjoin, butt, butt against, edge, march.

border (noun)	butt on (noun)
a strip forming the outer edge of something
a decorative recessed or relieved surface on an edge
a line that indicates a boundary
the boundary of a surface
the boundary line or the area immediately inside the boundary

border (verb)	butt on (verb)
lie adjacent to another or share a boundary	lie adjacent to another or share a boundary
extend on all sides of simultaneously; encircle
enclose in or as if in a frame
provide with a border or edge
form the boundary of; be contiguous to