What does the colour mean ?
The old technology, a.k.a. "conventional," a.k.a. "inorganic," is green in color.
Cooling liquids with a low silicate rate are amber or red and do not tend to separate from water as high silicate liquids would. They therefore offer a better protection and require less maintenance.
Source: Diverse

You should not move from Green to Orange
The promise of OAT (Organic Acid Techynology - orange, launched in 1996 by GM as Dex-Cool) is long-life corrosion protection, on the order of six years/ 100,000 miles for the initial fill instead of the two years/50,000 miles that was typical with the old green stuff. The GM Dex-Cool formula works fine in systems designed for it. But it eats old-style radiators with lead solder, and the inhibitors work too slowly to protect against the sort of corrosion that happens so fast it actually erodes metal-for example, the cavitation likely in the imperfectly designed water pumps of older cars.
"Cars born with green coolant shouldn't be changed to orange," Turcotte advises. It's also a bad idea to mix the two, although the result doesn't immediately turn into witches' brew.
Source: CarandDriver