A member at SEO Chat posted his test results for measuring the underscores versus hyphens both in the URL and in the title of the page. Does Google consider them to be the same? Well based on his early tests, the answer is NO.
The SEO Chat thread is is found at google underscore test results. You can view the test page here.
Notice the filename structure is (I italicized the text within the URL Google can read) chalcakloopy-cganveeeing_doreaivnically_phreanatoindment-bafdiadiiafy.html
Notice the title of the page is worded as (I italicized the text within the title tag that Google can read) teawufloppafomper-flevalitettaeilanvincely_capamafiandhfollicruxzst_audfivatrdatalnmafluzs-ahgonnvohunnytion
Now lets check Google results for those keyword phrases that match the URL structure: chalcakloopy is a match! cganveeeing is not a match. doreaivnically is not a match. phreanatoindment is not a match. bafdiadiiafy is a match!
Now lets check Google results for those keyword phrases that match the title structure: teawufloppafomper is a match! flevalitettaeilanvincely is not a match. capamafiandhfollicruxzst is not a match. audfivatrdatalnmafluzs is not a match. ahgonnvohunnytion is a match!
Nice test.
