Is the Gepard GM6 Lynx Sero and the Gepard M6 the same?

I've been trying to do research on the M6 with it's 14.5x114mm caliber round but every time I search it, the GM6 with it's .50 BMG round always pops up. Are the two one and the same or did the ocmpany just change it's mind from making it 14.5x114mm to .50 BMG or something?