Meaning 1
"take-off": the plane leaves the ground and is in the air; "fly": the plane is in the air
Sentence 1
With Rebecca in charge, this plan will take-off . With Harry in charge, this plan will fly.
Meaning 2
(Same as "to get something off the ground" ie, to be on the way to a successful conclusion)
Sentence 2
If you don't get your work done, this project won't take-off. Flying was a sport before it was a means of transportation.