Samsung Galaxy S3 I9300 was released in May 2012 & I9305 was released in September 2013

Key differences between I9300 & I9305 are as follows:

1. 4G- LTE (Long Term Evolution):

For those wanting superfast downstream/upstream rates, I9305 offers support to 4G . Expect downstream rates as high as 95Mbps if in good coverage. Unfortunately, the best selling variant of Galaxy S3 – I9300 does not support 4G – LTE

2. MEMORY (RAM):

I9305 has 2GB internal RAM , thus, speeding things up for this phone. I9300 only has 1GB internal RAM

3. COLOR VARIANTS:

The best selling model I9300 is available in many colors such as: Pebble blue, Marble white, Amber brown, Garnet red, Sapphire black, Titanium grey, La Fleur

I9305 is only available in 2 color variants: Titanium Gray, Sapphire Black

Clearly, the more recent model I9305 is a winner here, but ,Samsung always likes surprising us and hence looking forward to the release of Samsung Galaxy S4 in March 2013 .

Here is a comparison between both models (courtesy: gsmarena.com)

Comparison i9300 and i9305

Comparison i9300 and i9305