They are two distinct and different regimes

(Dr. Uma Suthersanen, Chair in International Intellectual Property Law, Centre for Commercial Law Studies, Queen Mary, University of London, United Kingdom“Utility models: Do they really serve national innovation strategies?,” pg online @ https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3139963 //pa-ef)

However, from the German perspective (and indeed, as we see below, from the East Asian examples), it is unarguable that a sui generis regime is useful in resolving or avoiding the deficiencies of the current patent system, in terms of cost and speed of securing protection, and in harnessing and diffusing indigenous technologies. One commentator lists the advantages of utility model registration in comparison to patents in Germany, as including: lower costs, lower thresholds in relation to novelty and inventiveness, quicker registration procedure, strategic means of obtaining full protection during the intermediate period between publication and actual grant of a patent.25 This type of reasoning can be easily extrapolated across other established, developed countries.