Larger ones are for commercial use. If you look closely, you may see some tiny dots on the screen. The closer the dots are, the sharper the image. Buy a monitor with at least 0.28mm dot pitch or less. This determines how much can be seen.
Lower resolution displays a larger area of an image.
Higher resolution allows for a full view but the image itself will be smaller. You may also consider a multisync monitor. This allows you to choose from different resolutions to suit your needs. The older models are interlaced. You will see the occasional flicker on the screen.