Differences in Waterfalls from Different Services

Does anyone know why the waterfalls of my website would look different from different services? I.E. WPT’s waterfall differs from Chrome Developer Tools’s which differs from Firebug’s. Typically, there are many more requests that show in WPT, and many requests are in a different order in the other services. Anyone know why this might be?

Are you clearing your cache and cookies before testing locally? That would be my initial guess without more detail.

Yes, I disabled the cache in all testing.