Question: What is the difference between the ads at top of page and right column of page?
Answer: Google displays ads on the top and on the right. If there are just a few ads, it may show ONLY on the right. There is no difference, in the sense that it is merely the algorithm looking at the a) bids, b) keywords inputted by the searcher vs. those inputted by the advertiser, and c) the quality score (QS) of the ad.
That said, many people prefer positions #1 (top position), #3 (right above the first organic result, where people look), and #4 at the top of the far right. I generally aim for positions #3 or #4 as I think those have the highest ROI in terms of AdWords spending.
on SEO | AdWords | Social Media