Ever run into the problem of needing to output data from a PHP loop into separate wrapping divs? You could use the same loop twice to return data into two different divs. Or you could use this is a super handy technique to generate data inside multiple different elements using the same loop.
If you are serving a lot of images on a page, using srcset is a really handy way to effectively cut down page size. WordPress does a lot of heavy lifting with it’s great image management and baked in srcset function, so much so you can forget about get_the_post_thumbnail() entirely.
These methods might seem simple and interchangeable, but for beginners it can be confusing and hard to understand where to use these tags appropriately. Personally, understanding how these two methods work helped me write more understandable and resilient code.