Down turned tweezers are great for weeds that have their base on the very surface or for pine needles that are on the outer canopy of the tree. Straight tweezers shine when a weed has a base or root system that is further down in the soil and you need a straight end that can go down into the soil and grab that bass. The straight tweezers are also great for being able to get deeper into the tree for needle plucking or pinching.