I see both SparkChess and flashCHESS mentioned. What’s the difference between them?

They are the same product. When we created the first game engine in 2002, we called it flashCHESS. Later, in 2008 the third generation of the engine, rewritten from scratch, took the web by storm and we wanted to keep the name due to its heritage, naming it flashCHESS III. Later, to prevent any trademark complaints from Adobe regarding the use of “Flash”, we decided to rename the game as SparkChess.

SparkChess® is registered trademark.