Yes, there may be a distinction between "elaborate" used with a normal direct object and "elaborate on" used with a prepositional object: the former, where it is used, tends to mean "create, establish", whereas the latter tends to mean "give further details about". If you look at these examples from the Europarl corpus:
you'll see examples such as:
"must outline a concrete strategy ... and elaborate a detailed investment plan"
where the implication does appear to be create a plan, not develop one already in existence, vs:
"elaborate a little on what you said".
where the idea is "go into more detail".
As an informal intuitive observation, I would have said that the first usage isn't very common. However, I did a quick check on Google ngram and the figures appear to belie my intuition:
If these figures are anything to go by, "elaborate on" appears to be a relatively recent innovation, vs a time when "elaborate" was practically always used with a 'straight' direct object.
Interestingly, as testimony to this being a relatively recent innovation, Websters 1913 edition doesn't appear to mention the possibility of "elaborate" with 'on', but gives the following definition and example of transitive 'elaborate':
"To perfect with painstaking; to improve or refine with labor and study, or by successive operations; as, to elaborate a painting or a literary work."