HELP OBD2 versus ECU

[greenking49]

Very new to all this,

is there difference between what information i can access from the OBD port under the steering wheel versus the port on the engine.
and is there a budget reader option that can give me all the information I would want.
I am US based if that matters

 

[t-tony]

The connector under the dash only reads the engine and Auto gearbox ECUs. ALL other accessed through the under bonnet nnet connection. Readers depend, largely, on your budget.

Tony.