How close is playing a guitar to playing an ukulele?

Different tuning but the ukulele is only half an octave long. many players do several fretted instruments.

The guitar and ukelele share a common tuning system. Chord shapes are identical but transposed. If you place a capo at the 5th fret of a guitar (and play only the first 4 strings) you have the same tuning as a ukelele. The only difference is that the 4th string is tuned one octave higher.
This means that a chord shape on the guitar is a 4th higher on the ukelele i.e. a standard G major chord on the guitar is a C major chord on the ukelele.

Well I've played guitar for 5 years now, and last year I bought an ukulele, and I can tell that its not quite the same.. Its different chords :)
But strumming is the same. You can't really do much finger play, as there is only four strings..
You can't tune an ukulele with a guitar tuner either..
Its weird, cause on an ukulele, its the 2nd string from top, that is the thickest..
Okay anyway, hope I answered your question :)