Pressure and Force are two things which are definitely similar. To find Pressure, you need Force. So, first I will explain what Force is. Force is any action which will move an object when unopposed. Basically, a force can cause an object with mass to change velocity, or to accelerate or decelerate. Also, a force can be push, or pull. Force is calculated by doing the following:
Force
As you can see, for this formula we can also use the triangle. F is equal to force, m is equal to mass, and a is equal to acceleration, but can be replaced with g for gravitational pull. The mass will always be measure in kg, and the g (a) will always be measured in m/s^2. Because it is gravitational pull, we will have the same value for it each time-as long as we are on earth. This value will be 9.8 m/s^2. As you can see in the triangle above, we multiply mass and gravitational pull together, giving us kg/s^2. But, Isaac Newton was the one who came up with this formula, and since kg/s^2 is a mouthful-and because he has a lot of ego-he said that every kg/s^2 was equal to one Newton, or N. Thus, we measure Force in Newtons.
Pressure
Pressure is something else. Pressure is the measure of force acting perpendicular to a unit area. We calculate Pressure by performing the calculation Force/Area= Pressure. Since force is measured in Newtons, and area is measured in m^2, the measurement that we get is N/m^2. But, since once again that is a mouthful to say, the measurement which people came up with was Pa, or pascals. Obviously, when we get to larger numbers, we would use kPa, which means that we would either multiply by 1000 to do kPa to Pa, or divide by 1000 to get Pa to kPa. That is what Pressure is. You can now see an experiment using Pressure.
In this experiment, after the bottle is filled with hot water, then the hot water is emptied, the air inside the bottle is still hot. Then, he quickly puts a straw inside the bottle, but it has adhesive clay on top. Therefore, the dense clay will block the hot air from exiting the bottle. So, when he puts the bottle inside the cold water, the air inside the bottle is still cooling down, meaning that there is a pressure differential between the water in the bowl and the air in the bottle. Because of this, the bottle creates a vacuum, which sucks up water until the pressure on the inside of the bottle is equal to the pressure on the outside of the bottle. That's one experiment which is really cool.