The Mac II could display millions of colours, but not at the same time.
From wikipedia:
"The Macintosh II includes a graphics card that supports a true-color 16.7 million color palette and was available in two configurations: 4-bit and 8-bit. The 4-bit model supports 16 colors on a 640×480 display and 256 colors (8-bit video) on a 512×384 display ..."
There were optional video RAM upgrades, but none that gave you 'millions of colours at 640x480'.
Wikipedia also notes: "The video card does not include hardware acceleration of drawing operations."
Also, for comparison, in 1987 when the Mac II came out (two years after the Amiga 1000) you could buy a Mac II for USD$5,500 or the Amiga for USD$1300.