Mainly look at the symbol series. At the bottom right of the picture, there is also a list of categories, including orange (rare), gold (rare), silver (unusual), black (ordinary/basic/derivative) and purple (special).

Some old series, the core series A/B/U/R/4/5, have no series symbols (Chinese version 5 has series symbols, and the rarity can be judged), and the expert series has series symbols before the book of Reith (excluding the book of Reith), but there is no color difference in rarity, and there is no difference in rarity between the primary series Bo Tu and Bo Tu 2.

There is no way to distinguish these through series symbols, only through official and unofficial databases.