Why it is easier to stop a tennis ball than a cricket ball moving with the same speed?

Well, you have to absorb the kinetic energy, work out the kinetic energy for a tennis ball and a cricket ball travelling at the same speed.

Absorbing all the kinetic energy makes sense, but Wikipedia (last time I looked) states that momentum essentially represents how hard it is to stop something. Since kinetic energy and momentum have different formulas, can someone explain in greater detail?

Try absorbing all the kinetic energy

In simple terms when the cricket ball comes in contact with your hand it expends more kinetic energy as it has a greater mass. The tennis ball is lighter and expends less kinetic energy.

According to the principle of "Conservation of Momentum", this makes lot of sense.

A cricket ball, having much greater mass than a tennis ball, has a much greater momentum than the latter.

When the cricket ball hits my hand, and if I do not, for example, move my hand while it hits my hand, the skin and flesh of my hand are given the momentum of the ball and therefore I hurt a lot: I donot move my hand, but the skin and flesh of my hand get a lot of impact. My hand stays still, but skin and flesh move. They move much faster than in the case of tennis ball because of greater momentum of
The cricket ball.

That's why, it is advised that while catching a moving ball, especially a cricket ball, we move our hand backward. In this way it will hurt less.

Another approach:

Rate of change of momentum = impressed force

The momentum of a Cricket ball being much more than that of a tennis ball, the force
required to stop a cricket ball is much more.

Hence more force (action and reaction) accurs between your hand and the cricket ball

You can also consider inertia. A body of higher mass (cricket ball) is more difficult to stop than one of lower mass (tennis ball)

tennis ball's momentum is lower than cricket ball , because mass is law
momentum= mass* velocity
F=change of momentum/time
so easier to stop a tennis ball

This is correct. Change in momentum is related to force, not energy.

It is because of momentum...
We alll know that rate of change of momentun with respect to time gives the force exerted... thus we observe that force exerted by cricket ball is greater