When you perform free tests with 4Gmark, you participate in a collaborative project to aggregate a base of information for understanding and improving the quality of service.
The "Speed Test" quickly calculates downlink and uplink network speed (average Bitrate).
At the end of the Test, in the results, you can benchmark your results against the average bitrate obtained by other users in your country, in the same area or using the same smartphone (wifi or cellular).
The "Full Test" is a scenario with all protocols (latency, transfer, youtube, web) giving full visibility over the quality of the connection environment. It calculates a score which let you compare between them different smartphones, networks or places.
At the end of the Full Test, in the results, you can benchmark your results against the average score obtained by other users in your country, in the same area or using the same smartphone (wifi or cellular).
Also in the "Custom Test" section, Customized scenarios of tests are available.
Finally as a bonus, a dashboard that will offer the most current real-time information about your hardware, your location, your cellular and your wifi connection.
You can check your microphone (record & listen), multitouch, internet connetion, dead pixels, accelerometer etc.
Also there's a list of device parameters including all important information and the small render test (that's for my personal researches tho, thanks for running it).