What's the difference between basic card and concept card?

I can’t seem to understand what the diffrence between a :: card is and a >> card is as the descriptions I think are the same and they do the same thing. Maybe I’m being dumb but I am very confused.
If anyone understands this please explain: it would be helpful :+1:

Concepts are by default biderectional, are automatically bolded, and have higher search priority (a separate section). Other than that, they have the same cards as the Basic.