If you click on the label of a track column, that column will be sorted in alphabetical order. The sort will ignore case if the A=a check box near the top middle of the playlist window is checked. If you have manually edited the playlist you will be asked if you want to sort the list and discard the previous edits.
The track column is a special case. Clicking on either that column or the album column will first sort by album and within each album will sort by track number.