Since I've often seen the piano solo parts to concertos uploaded here as though they were "piano arrangements", I'd just like to recommend comparing piano solo parts with actual arrangements like, say, Beethoven symphonies as arranged by Liszt (his arrangements as a general thing include some very good examples; his students' arrangements perhaps likewise) - complete piano pieces*, sometimes changed here and there from the original for greater piano effect (a valuable thing, not negative- "arrangement", not transcription, the whole point is to create a working piano piece that conveys the spirit of the original while taking advantage of the medium to hand- etc.)
(Note that we list cadenzas under arrangements too so just looking under the arrangements category is only a start.)
*Or in the case of some of his arrangements, duet or 2-piano pieces, etc. Same general idea, though.
Arrangements vs. parts
Moderator: kcleung