Yeah, as PG mentioned both are great tools & I had just run a demo test with Solomon facial plastic & it seems that both are delivering great insights on page speed.
Google Page Speed:
Google page speed gives is giving an over all score after running the performance of the site. It also gives suggestion summary with High Priority, Medium & Low priority & experimental rules. High Priority encompasses Leverage browser caching, Enable compression, Optimize images & this should be addressed first for getting faster speed & enhanced site performance.
Medium Priority :These are the ones you should address after the high priority one. It includes Combine images into CSS sprites, Defer parsing of JavaScript, Serve resources from a consistent URL etc. Next comes the low priority & experimental one. Please see the following results associated with this.

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Pingdom Tool:
This is another tool for testing load time of a site. It also gives great insight on page speed performance encompassing Leverage browser caching,Avoid bad requests,Remove query strings from static resources,Minimize redirects &Minimize request size. It also gives page analysis with server response codes.

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