Yesterday was Amber (drop in HRV), but I trained pretty hard anyway.

Today (05/09/2013) my HRV has jumped to 90. The App (Android v2.0) shows this as Green while the site shows Red (readiness=4).

Which one is correct? I need to know whether I should train today or not.

I've read Joel mention elsewhere that the App is correct, but based on how I feel and my activity yesterday the website result seems more likely.

Please help, thanks.

Again, the only way the data points could be off is if you were deleting entries in either the web app or device app without deleting that same entry on the other, OR if you have logged data entries on multiple devices. This would cause a difference in the device and web app readings. You will have to go back and look through your data entries and compare both to make sure the data points line up and match correctly.