Now, some buckets are worth more than others, and the three main buckets that you need to be aware of for search rankings are quality, trust and authority. So quality: what Google is trying to measure when they’re trying to figure out what sites should rank is offering something valuable or unique or interesting to googles searchers. For example: good content—if you are selling t-shirts and you are using the same description that every other t-shirt seller is using on their website then you are not offering anything unique to Google’s searchers.
This is not possible for everyone. But in some cases, in the case that you're getting into Google news, or in the case that you're in the recipe world and you can get visuals and images, or in the case where you have a featured snippet opportunity and you can get the visual for that featured snippet along with that credit, or in the case where you can get rich snippets around travel or around flights, other verticals that schema is supporting right now, well, that's great. You should take advantage of those opportunities.
The key distinction is that SEM is a broader strategy which combines paid search and SEO tactics. So, if you set up a PPC advertisement, but don't take steps to optimize the ad or the website it links to, this is a standard example of paid search. However, if you optimize your site and your search content with solid keywords, then you put money behind it to boost it on targeted audience's search pages, then you're dabbling in SEM.