comScore released its reports for the top 50 web properties in the U.S. and U.S. search market share today. The two reports may have a direct relationship in terms of the market share fluctuation between Google and Microsoft.

In the top 50 web properties report, comScore revealed that Google sites, while still on top, dropped from 190 million unique visitors to 187 million from July to August. Microsoft sites went up from 169 million to 170 million.

In the search engine report, we also see Google dropping a bit, and Bing rising. Google went from 66.8% in July to 66.4% in August, while Bing went from 15.7% in July to 15.9% in August.

The share percentage for the Search Alliance between Bing and Yahoo is slightly different than the total combined number of Bing and Yahoo search share. The comScore report breaks out “powered by” search numbers for both Bing and Google, with the most recent Search Alliance share at 25.3%. The reason for this slight difference is that Bing doesn’t entirely power all aspects of Yahoo search.

As with the Top 50 report, comScore has changed its methodology a bit. The firm says, “The first enhancement is the incorporation of updated demographic universe estimates based on data from the 2010 U.S. census, which provides an improved accounting of the percentage of the population falling into each demographic segment. The second enhancement was an improvement in comScore’s enumeration survey methodology to better represent persons in cell-phone only households.”

Because of the changes, the report excludes month-over-month changes.