Microsoft is trying to simplify things for Windows 10. The "universal apps" that run across PCs, phones, tablets, and the Xbox One will simply be called "Windows apps". We have been calling them "Metro apps" since the announcement of Windows 8 because Microsoft used "Metro" to refer to the design language that the company used for its Windows 8 apps. This confusion goes even further when the company dropped the Metro name altogether because of some trademark issues. So people started calling these apps "Modern apps" and "Windows Store apps". Microsoft has now settled on its naming, allowing us to forget about Metro. 
The old traditional software will be called "Windows desktop apps" which run on PC only.