any reason for not using product?
While your playing your role as an individual developer then you can say "Application", but when you are presenting a company then you can say "product". But normally max people are using "Apps"
I think application is more suitable as now a days its a common term used by everyone. Product is used when you are referring a company or an organization as companies and organizations have more than one product so they use term product but as an individual you can use application.
If you are selling it I would call it product.
If it was made for your own in house uses then I'd call application.
One more question:
Is "app" and "application" the same thing? or do they have a diff meaning technically?