1st version (gold ring): maximum magnify ratio: 1:2, but only at 300mm side
2nd versoin (red ring): maximum magnify ratio: 1:2.9, can do macro from 200 to 300mm, it's 1:2.9 at 300mm side, 1:5.x at 200mm.
2nd version has some improvement on the glass, that's what I heard, not really sure.
Both are quite decent and cheap lenses. Buy either one and you won't regret for the price you pay.
The 70-300 at f5.6 output is better than the Sigma 70-200 + 1.4x at f5.6.....(this(70-300) is a very good lens for sunrise/sunset...where you wnat to have a sun ball in photo.....do not use this lens with UV filter attached......lots of image gradation is by UV filter.....)