There are different techniques when it comes to holding the nozzle, pushing or pulling the weld, or nozzle movement. The weld on the left was pushed left-to-right with the nozzle at the correct 45-degree angle. Pushing puts the shielding gas out in front of the weld, but can be harder to watch the puddle. The weld on right was pulled left-to-right and is a bit more even but if there were any impurities on the material, it could’ve contaminated the weld more easily. Either way, make a series of cursive-shaped “Es” starting at the bottom of the material and looping upwards: bottom-to-top. When working vertically, it’s always easier for the novice to start at the top and drag the weld downwards.