Cracklinburg, still seen as the name of the town in this map, turned into Laytonsville, which is noted here as the name of the Post Office. It was not uncommon for places to have multiple names according to the interests of the individuals naming the area. Typically, interests that alligned with post offices tend to win out.
However, that was not the case with Gaithersburg. The area was known as Log Town in the 1700s. Around 1802, Benjamin Gaither established himself in Log Town and began to build up his sphere of influence. Informally, the area became known as Gaitherburg. The Post Office established in 1851 ignored this designation and referred to itself as Forest Oak PO with respect to the large tree located next to Gaither's store. By 1878, it appears that this issue was resolved with the area cementing itself as Gaithersburg (now with an S).