You can get to the transaction detail view by clicking on the > arrow to the right of a transaction in the flood view. The transaction detail view drills down into the metrics of the transaction selected, as well as displaying Headers, Assertions, and Errors.
On this screen, you'll see data that is specific to the transaction you've selected, whereas the flood view gives you a quick way to see how your flood ran as a whole.
The green bars in the test represent the number of passed instances of this transaction. Flood reports HTTP 200s as passed and all HTTP 4xx and HTTP 5xx as failed by default. Adding validations or assertions can change this behaviour.
There are a few icons that you may see in the Transaction Detail View that come in different shapes and sizes. These icons correspond to status codes.
green diamonds - HTTP 200 purple crosses - HTTP 4xx red square - HTTP 5xx blue circle - non-HTTP response
The data in the transaction detail view are taken from the load testing tool you used, so you can expect some differences in what is displayed due to differences in what each tool records.
For example, a unique feature of Element is that it can take screenshots during the test. These screenshots are displayed below the bar chart:
Scrolling down farther, you can also see the headers as well as the request and response bodies. This is a great way to see what errors you're getting and why.