The difference is that you're throwing ad-hoc enhancements on top of an underlying framework which can't be modified beyond its basic principle. Yes, if you are

The difference is that you're throwing ad-hoc enhancements on top of an underlying framework which can't be modified beyond its basic principle. Yes, if you are looking for exact or simply scaled duplicates on other websites, a vector search for downsampled images would work ok. However, SIFT/SURF has a much more principled approach that can can be extended to handle more cases "when you need it." It's the difference between hand-writing HTML and using a template engine. On one scale, of course it makes sense to just copy and paste some HTML. But as things get hairier over time, you have to switch to something more powerful.