High end 'boards offer: More high spec connections: 6Gb/s SATA, USB 3.0 and PCI-E 3.0. They'll usually accept more, faster memory and have more sophisticated memory/HDD controllers. They support a wider range of overclocking options and more stable power delivery-an important feature for said overclocking. Some support very high quality sound, either directly on the 'board itself or through a provided add on (daughter board) card. They all support at least dual graphics cards some can support up to 4.
Low end 'boards reduce all these features with fewer SATA/USB/PCI-E connectors and may totally lack support for overclocking/Crossfire/SLI although more than a few will support dual cards they often do so at lower connection speeds.
Unless you plan on serious overclocking or need dual PCI-E 3.0 x16 slots a mid/low end 'board will be fine.