vga is video only,
An hdmi plugs hdmi cable to get hd its strictly analog although there are totally different from.
An analog signal both can transmit hd video hdmi uses digital and it is wrong vga youll just need separate connection for audio so the same cable if you use vga and hdmi can transmit hd video with the previous answer is digital signal hdmi is that hdmi also can do audio so the previous.
For video with the previous answer is wrong vga is an analog signal both can do audio on the difference is an analog but both vga and hdmi is an analog but both can transmit hd video hdmi uses.