In lang=en terms the difference between bar and arrest
is that
bar is one of those musical sections while
arrest is the act of arresting a criminal, suspect etc.
In farriery terms the difference between bar and arrest
is that
bar is the part of the crust of a horse's hoof which is bent inwards towards the frog at the heel on each side, and extends into the centre of the sole while
arrest is a scurfiness of the back part of the hind leg of a horse.
In transitive terms the difference between bar and arrest
is that
bar is to lock or bolt with a bar while
arrest is to catch the attention of.
As a preposition bar
is except, with the exception of.
As a proper noun Bar
is a city in Montenegro.