A motorcycle center-stand is intended primarily for maintenance work, not for routine parking of a bike. It allows you to get one (or both) of the wheels off the ground to enable chain maintenance or removing one or both of the wheels. By default (on most modern bikes) it is the rear wheel that is lifted. By lifting the rear wheel, you will no longer have any of the “parking brake” effect of putting the bike in gear to help prevent the bike from rolling forward. The side-stand is the one intended to be used for parking. It is considerably more stable laterally than a center stand. It takes much more effort to high side a bike (push over to the right) from the left side, side-stand than it is to tip it sideways off of the relatively narrow footing of a center-stand. And it is completely stable to the left against the stand’s wide leg, so long as the bike doesn’t roll forward. This is why when you take a ferry over rough water they always have you put the bike on the side stand – NEVER on the center-stand. They also sometimes take precautions to keep the bike from rolling forward (chocks) and high siding (strap bike against the side-stand to the left). With the bike in gear, a side-stand is also more stable in the forward direction of the wheels. Both stands are devices that only lock into place by the gravity of the bike being “over centered”, i.e. past the highest point of the stand’s deployment arc. In both cases the stand folds to the rear, so that if the bike is pointing downhill (even a small amount) it is more likely that it will want to come off of the stand. If the bike is pointing uphill it is actually less likely that it will want to come off the stand than it is on level ground, and in fact it can be difficult to get a bigger bike off the center stand if the hill is too steep.