Well, the colors sort of indicate the read/Write speeds capable. Really, you want to look for a number inscribed in a “C,” or “U” shape:Read the below article excerpt:

Picking the Right SD Card: What Do the Numbers Mean?https://www.google.com/amp/www.a...

Class 2 – these cards are the slowest class currently available and are best suited for consumer-level point-and-shoot cameras, audio recording, and low-resolution SD video recording.

Class 4 & 6 – the “middle of the road” in terms of speed, these cards will work well with still cameras shooting jpeg files, and some very light HD video recording at 720p.

Class 10 & U1 – these cards are capable of recording at up to 10 MB/s, so they are well suited for pro-level still cameras shooting RAW photos, and HD video recording at up to 1080p. This is a great speed to purchase if you’re looking for a balance between compatibility with your current equipment and future usage as well.

U3 – these cards are overkill for most uses, but are absolutely crucial if you’re shooting 4K video with your device. 4K video files are large, and require a card with a high sustainable speed to be able to write them properly. U3 cards are quite a bit more expensive than the slower speeds, but if you need them, you really shouldn’t risk using anything slower.