Not quite. You may be getting confused about which technique is used in a crosswind and which one is used in normal winds. The oncoming (relative) wind in both manuevers is from the side, whether it be a normal wind or a crosswind. Here's another rundown of both manuevers. Both of them are slips, as the nose is turned away from the oncoming wind. Both airplanes are tracking straight to the runway. I use the term "steer" rather than "add aileron" because it's clearer.

1) "Slip". Encountering a crosswind, pilot needs to do something to correct for it lest she be blown off the runway centerline. They put the upwind wing down using the yoke, and add as much rudder as needed to keep the aircraft from flying in the direction the wind is coming from. If crosswind is from right, turn yoke to the right, right wing will be down left wing will be high, add some left rudder to align airplane with the runway. Fly down the extended runway centerline. Airplane touches runway on upwind wheel first, then settles down on the downwind wheel.

2) "Forward slip". This is primarily in non-crosswind conditions to lose altitude. Rudder drives the manuever, in contrast to above where rudder merely compensated for off-alignment. Choose a rudder, doesn't matter which, stomp hard on it to get a big yaw. Left rudder causes a left yaw for example. Airplane turns sharply left, push hard on yoke to get rapid descent, and counter the tendency to go left by steering a little right as required. 100 feet or above the runway drop the control inputs and straighten the airplane.

A variation of this manuever occurs when one has both a need to lose altitude and a crosswind at the same time. Select the rudder that yaws the airplane away from the oncoming wind, so to get maximum side exposure to oncoming wind. Right wind, use left rudder. Everything else is the same, except it will take a lot more right steering to keep from going left. Do not make the mistake of stomping on the upwind rudder pedal, as this will remove drag rather than add it. This would actually set up a crab or a skid, rather than a slip, and rapid altitude loss due to increased drag will not happen.

Another altitude losing technique, which also serves to slow the airplane down and take up time, is the S-turn. Turn left then turn right, then rinse, wash, and repeat. This adds drag with all the banking, adds time with the added distance, and loses altitude for both the above reasons. It doesn't look or feel very good, it tends to result in youtube vidoes, so for this reason is not preferred. If no one is around and you did a sloppy job of setting up your approach you can use it, otherwise you had probably better go around.