The biggest difference in different sonar technologies (2d, DI, SI) is the shape of the sonar beam that affects where in the water column that return came from that you see on your screen...

2d is a cone emanating from Xducer in a downward direction...

DI & SI are a thin slice emanating down and out to the sides 90 degrees from the Xducer...

So , CP, to answer your question....although your image may look similar to 2d image... Where that structure actually is under your boat depends on which shape beam you are sending thru the water...

If you are using 2d... Then that structure is in that cone shaped beam alwost directly under the Xducer...

If you are using DI... then that structure is in that thin sliced beam "somewhere"...

If you are using SI... that the unit will show you which side of the boat that structure is on...

Clear as mud yet...??

Rickie