spare

As adjectives the difference between plain and spare

is that plain is while spare is scanty; not abundant or plentiful.

As nouns the difference between plain and spare

is that plain is (rare|poetic) a lamentation or plain can be an expanse of land with relatively low relief while spare is the act of sparing; moderation; restraint.

As verbs the difference between plain and spare

is that plain is to lament, bewail or plain can be (obsolete|transitive) to plane or level; to make plain or even on the surface while spare is to show mercy.

As an adverb plain

is (colloquial) simply.

In lang=en terms the difference between substitute and spare

is that substitute is to serve as a replacement (for someone or something) while spare is (to give up) to deprive oneself of, as by being frugal; to do without; to dispense with; to give up; to part with.

As verbs the difference between substitute and spare

is that substitute is to use in place of something else, with the same function while spare is to show mercy.

As nouns the difference between substitute and spare

is that substitute is a replacement or stand-in for something that achieves a similar result or purpose while spare is the act of sparing; moderation; restraint.

As an adjective spare is

scanty; not abundant or plentiful.

In lang=en terms the difference between expense and spare

is that expense is to charge a cost against an expense account; to bill something to the company for which one works while spare is (to give up) to deprive oneself of, as by being frugal; to do without; to dispense with; to give up; to part with.

As nouns the difference between expense and spare

is that expense is a spending or consuming often specifically an act of disbursing or spending funds while spare is the act of sparing; moderation; restraint.

As verbs the difference between expense and spare

is that expense is to charge a cost against an expense account; to bill something to the company for which one works while spare is to show mercy.

As an adjective spare is

scanty; not abundant or plentiful.

In lang=en terms the difference between reprieve and spare

is that reprieve is to bring relief to someone while spare is (to give up) to deprive oneself of, as by being frugal; to do without; to dispense with; to give up; to part with.

As verbs the difference between reprieve and spare

is that reprieve is to cancel or postpone the punishment of someone, especially an execution while spare is to show mercy.

As nouns the difference between reprieve and spare

is that reprieve is the cancellation or postponement of a punishment while spare is the act of sparing; moderation; restraint.

As an adjective spare is

scanty; not abundant or plentiful.

Spare is a related term of skinny.

As adjectives the difference between spare and skinny

is that spare is scanty; not abundant or plentiful while skinny is (informal) having little flesh and fat; slim; slender; narrow; thin, generally beyond what looks beautiful.

As nouns the difference between spare and skinny

is that spare is the act of sparing; moderation; restraint while skinny is (colloquial) the details or facts; especially, those obtained by gossip or rumor.

As a verb spare

is to show mercy.