As nouns the difference between propositions and plans
is that propositions is plural of proposition while plans is plural of lang=en.
As verbs the difference between propositions and plans
is that propositions is third-person singular of proposition while plans is third-person singular of plan.
propositions
English
Noun
(head)
Verb
(head)
(proposition)
----
plans
English
Verb
(head)
(plan)
Noun
(head)
Arrangements to go on a trip.
----