What is the difference between organic ranking (SEO) and paid ranking (SEM)?
Organic search ranking is usually due to SEO, and paid ranking is usually due to SEM. If your site ranks highly in the organic rankings on Google, then you have most likely gotten there because you have a solid SEO structure backed by well written content that others find valuable. In contrast, those ranking among the paid rankings on Google have usually gotten there due to paying for placement for particular keywords using Google Adwords.
Another way to think of organic rank vs. paid rank is to compare them to magazine advertisements. If someone is said to be organically ranking high within a magazine, they would be the entity receiving a writeup, whereas someone with a high paid ranking has paid for an advertising spot within the pages of that magazine. It is much harder to get a free mention in a magazine than it is to pay for an advertisement, but the benefits can be similar. Ultimately you want to strive for high organic placement, but well executed paid placements also serve a purpose.
Which is better – a high organic search ranking or a paid ranking?
Each have their benefits, but only a paid ranking has a drawback (the money you spend to be listed within the paid search results). Everyone should always be working to be listed higher within the organic rankings, but not everyone is going to see a major benefit to using paid placement advertising to drive traffic to their website.
At the end of the day, both a a high organic search ranking or a paid ranking will get you hits. The only question that remains is – once those visitors arrive at your website, will they stick around long enough to complete the call for action you have laid out for them? Is your site structured well enough for them to see the ad you want them to click, buy the product you’re promoting, or join the cause you want them to be a part of?