I'm sure someone could explain ?
Reliably I'm told that they are different configurations....
Anyone help to explain.

Cheers,

Gastro

Both exactly the same. Boxer/Flat both describe engines with opposing cylinder layouts.

Ahh - but I've just found this....

The 911.....It is not a boxer design. A boxer engine has not only a 180 degree layout, but has a flat crankshaft arranged so that the matching pistons are at top-dead-center at the same time (so that the pistons move, alternately, toward or away from each other).

Gastro

So the 911 doesn't have a flat-plane crank? I thought it did?