historic, historical
historic means an important event in history
historical means dealing with the subject of history

impact, impactful
impact does not  mean to affect something [use affect or influence]
( This affect the team, not, this impact the team.)
impactful is not a word [use effective, forceful, compelling, impressive]
(The seminar was effective, not the seminar was impactful.)

imply, infer
imply means to suggest indirectly
infer means to conclude