The Stella and the PX150 are in fact very similar.

This is neither an accident nor is it a case of imitation.  LML (the company that builds the Stella) built the PX in large quantities in cooperation with Piaggio for several years.  These PX's were badged "Vespa" and sold in many countries.  This was not a case of licensing technology to LML, as was done with Bajaj in the 60's, but rather LML Vespa was a joint venture in which Piaggio owned 26% of the LML company. This is a significant percentage when you consider that 48% of the company was publicly traded stock.

LML not only built the PX, but they also made many of the components used by Piaggio in Italy to assemble other models. This includes the engines.  Even the 200cc motors were made in India, with the exception of the cylinders.  In fact, the current PX150 uses many india-made parts. But there is nothing wrong with being made in India. For years, whether they know it or not, vintage enthusiasts have been keeping their old Vespas on the road courtesy of India.   Last year I paid a small fortune for a performance ignition system for the PX (I intended to install it on a Stella).  I ordered it from Germany.  I was surprised to find that inside the box I found an LML CDI unit--the same as is standard on the Stella.

Compare the technology of the Stella with the technology of the PX150, you may be surprised.