Mechanism difference and what it means for holding force
A squeeze (trigger) clamp uses a ratcheting bar mechanism — you squeeze the trigger repeatedly to ratchet the jaw closer, and it holds at whatever force you ratcheted it to, up to its rated max. A spring clamp uses a fixed spring under constant tension — you squeeze the handles open, release onto the workpiece, and the holding force is whatever that spring provides. There’s no adjusting a spring clamp’s force upward the way you can keep ratcheting a trigger clamp.
Where each one wins
Bessey EHKL12 Trigger Clamp
Squeeze/trigger type — manufacturer rates it for real holding force (300 lb), suited to assembly and light glue-ups.
View Price on AmazonBessey XM5 Metal Spring Clamp
Manufacturer markets it for light-duty holding — quick tack-down of small parts, not structural glue-up pressure.
View Price on AmazonWhich to buy if you can only get one
If the job is holding boards under real pressure during a glue-up, the trigger clamp’s rated 300 lb force is doing actual structural work. If the job is just tacking a small part in place for a minute while glue sets or you drill a pilot hole, a spring clamp is faster to grab and release one-handed and costs less per unit — but it’s not a substitute for a trigger or bar clamp on anything that needs real clamping pressure.