What is the difference between the red circle and the non-red circle of Sigma lens?

Sigma gold rings represent professional lenses, red rings represent mid-range specifications, and low-end products have no rings.

70-300 This specification has two smart horses, one with a red circle and the other without a circle. The difference between the two seems to be that the red circle has more macro functions.

Note that the high, medium and low end here refer to "specifications", such as 24-70/2.8, which are used by many professional photographers, but it does not mean that Sima lenses with the same specifications can meet the professional requirements.

The advantage of 70-300 4-5.6 macro lens is that it is very cheap. As long as it is around 1200 and the telephoto reaches 300, it can also provide quite playable quasi-macro function. But don't expect too much from it in terms of image quality and workmanship: the overall plastic feeling is full, the focus ring is loose, the AF is slow and unpredictable, and the imaging of 250-300 segments is outstanding. If you are psychologically prepared for these problems and just want to spend as little money as possible to buy a cheap telephoto, it is not entirely optional.