The baseball player has thrown the ball and, according to Newton's First Law of Motion , an object (the ball) in motion stays in motion and an object at rest stays at rest.
The tennis ball went farther, wow!
An object in motion will stay in motion with the same velocity unless acted on by an external force. So the ball stays in motion until it contacts the other baseball player's glove (the external force) . The ball ceases its motion because the momentum of the ball is not as powerful as the glove.
Newton's Third Law
I'm gonna hit the ball!
The tennis ball and the baseball are thrown at the same force. Newton's Second Law states that acceleration equals force divided by mass and so the tennis ball would go farther because it has less mass.
Proven by Newton's Second Law, the tennis ball goes farther due to the fact that it has less mass.
The ball was thrown and the baseball player hit the ball. Newton's Third Law states that with every action there is an equal and opposite reaction, thus the baseball being pitched is the action.
The opposite reaction is the player hitting the ball and the reason the ball went forward is because the player's mass is greater than the baseball's mass.