Seems it thinner on screen or on print or both?
If on screen only, then try to adjust the font display (Cleartype on/off).
This tutorial is suitable for windows 10 too:
Dear Fenja, both... on print and screen and it's only this one font.
Not knowing what exactly you've tried, I'll just list what comes to my mind as possible sources of the problem:
Same font style / all 4 font styles available?
Graphics driver (another one than that of Win 7?)
Graphics driver by Microsoft or by the manufacturer of the graphics card?
Display profile (conflict between Adobe / monitor / Windows profiles)
Same paper / ink / toner cartridge type as before?
Printer driver (another one than that of win 7?)
Printer driver by Microsoft or by the manufacturer of the graphics card?
Printer settings (PDF settings if applicable)
Print (service provider)
All settings on the part of the service provider