Open Tunings...

No, it's much the same, although the usual open chord shapes don't apply..for instance, in open D ( DADF#AD, just drop the 1st and 6th to a D, tune the 3rd to the 4th on the 4th fret and the 2nd to the now F# 3rd on the 3rd fret) only a flat bar ie: only the index finger, is needed to produce a major chord anywhere up the fretboard. The 5th fret barred is then G Maj and the 7th fret A Maj..the open strings are playing a six-note D chord so the shape is already there, you just have to bar it. A good example if you would like to hear open tunings like this working in a mainstream piece of music rather than blues and bottleneck slide where it is more common is Tom Petty And The Heartbreakers "'Something In The Air""- the original Thunderclap Newman version is in Open E ( EBEG#BE).
Applies a lot to Resonators and anything with slide like one or two WhiteStripes pieces - Dobro tuning is another, as is open G, Keith Richard's favourite.
The effect, if you play blues, is of two guitars.