A home which is designed specifically keeping the interests of a particular client in mind using a specialist builder and architect is called custom home. There is no pre-designed plan at all in case of a custom home. The builder goes about the construction of the home using a unique plan designed specifically for a client by the home designer or the architect. In case of a custom home, the homeowner is heavily involved during the whole project. But, that is not the case with a pre-designed home wherein the client shows very little or no involvement until the construction is complete.
In case of a pre-designed home, the builder works on many homes at once using the same plan. But, in case of a custom home, the builder concentrates only on one home at a time and moves on to another project only after the completion of that particular project. Of course, there are exceptions to this fact wherein some large custom home building firms work on several projects simultaneously because of their resources at their disposal. Even in that case, they would have different plans and designs for each home.