Most tripods in this group have three leg sections, although the Hama Omega Carbon II has four sections. Each joint between sections is a potential weak spot that can introduce extra flexing in the leg, so fewer sections can aid stability.
With extra leg sections, the bottom ones also tend to end up being quite thin and spindly, and you need to operate more section locks when extending the tripod to its full height.
The flip side is that more leg sections enable the tripod to collapse to a smaller length for carrying. Less substantial 'travel tripods' often have four or five sections, so they can fold down really small.
For clamping each leg section during adjustment, the two choices are twist-locks or clip-locks. The latter have become far more popular, as they tend to be quicker and easier to use. The only real problem with them is that locking action firmness can be lost over time.
The ability to swing each leg out to multiple angles from the centre column is now featured on most tripods. In this group all tripods enable three different leg angles, apart from the more generous Jessops Major and Manfrotto 055XPROB + 496RC2 head, which give you four.
Multi-angle legs are great for shooting on very uneven ground or for reducing shooting height.
A neat feature of the Benro FlexPod A-297EX + BH2-M head, Giottos MTL9361B + MH1311-652 head, Manfrotto 055XPROB + 496RC2 head and Vanguard Alta Pro 263AGH tripods is that they have pivoting centre columns. This enables you to extend the column to its maximum height and then rotate it. It's great for macro shooting, as well as for ensuring you don't get tripod feet in the picture when using an ultra-wide-angle lens.