Energy

Each alternative has a positive aspect and fortunately these aspects can be combined.

"Contributing" and "creating" are examples of assonance--the initial "k" sound unites the thoughts.

The imperative tenses, "Give" and "Bring" are more forceful than the softer participles "contributing" and "creating".

Go for the best of both worlds: "Contribute energy, create harmony."

Cool.

Tlhanks.

The second phrase is more forceful because it is an imperative sentence...in other words, it is commanding someone to do something, without caring if they want to do it or not.

The first is not a sentence at all, but a conjunction of two noun phrases...which would most likely be used in a declarative sentence. Declarative sentences simply point out the facts.