UK One Pound [resuelto]

Hello,
does anyone knows what BU ( in KM# 975 - https://en.numista.com/catalogue/pieces1397.html ) stands for?
And how can I tell the difference between that and the common coin? Thanks.

BU = Brilliant Uncirculated

Cita: "Andy289"​BU = Brilliant Uncirculated

​And those coins are manufactured in the same way as the regular ones, or the process is different (like proof coins)? Thank for your replies.

It's all about the quality of the coins. Brilliant uncirculated coins are a higher standard than circulating coins because dies used to strike BU coins are polished and finished by hand. Although the quality of BU coins are better than usual coins but lower than proof coins.

Cita: "Andy289"​It's all about the quality of the coins. Brilliant uncirculated coins are a higher standard than circulating coins because dies used to strike BU coins are polished and finished by hand.

​Thanks for all the info!

These are coins that were issued in mint sets, I presume?