Lifts, 4-Bar, 6-Bar, and DR4B

A four-bar is two parallel bars moving together. The lifted end stays parallel to its mounting point through the whole range of motion, which is why it's the most common lift in VEX, simple to build, predictable to tune.

A six-bar is a four-bar stretched taller. Same principle, longer arms, more reach. That extra length means more torque is needed to lift the arm, and creates more friction at the joint, plus more tipping risk under load. Still easier to build and maintain than a scissor lift.

A DR4B stacks two four-bars, one reversed. The second linkage mounts where the intake would normally sit and faces the opposite direction of the first, letting the whole lift rise almost straight up instead of forward-and-up, and keeps the load's weight centered over the robot instead of hanging out front. It's one of the more complicated lift designs in VEX competition, budget extra build and tuning time.

A cascade lift isn't a linkage at all. It's a lift that delivers a lot of height while taking up very little space, stages telescope out in sequence on string or chain instead of rigid bars. Completely different build and tuning problem than any bar lift.

Match the lift to the game, not the other way around. Height in a tight footprint, cascade. Keep weight centered while going nearly vertical, DR4B. Simple and reliable at mid-height, four-bar or six-bar.