Integrated means it is a graphics "card" chip fixed on the motherboard that normally uses the normal memory for graphics purposes. Discrete normally means it is a separate card with its own memory. In more expensive laptops you can have both of them. The integrated ones are for the easier tasks and usually more battery efficient. The discrete ones are normally more powerful but more power intensive. So in most cases you can expect that the discrete ones are more powerful.
I am not familiar with those particular ones. However Revit is not that heavily dependent on graphics cards. A reasonable graphics card is usually good enough for Revit. Memory, CPU and fast hard drive/SSD are usually more important for performance.
Louis

Please mention Revit version, especially when uploading Revit files.