I wanted to add Salvia sclarea ssp. turkestanica and S. sclarea ssp turkestanica alba, but I was redirected to the Salvia sclarea. They look very similar, so please can someone explain me why several websites still use the ssp. turkestanica?

The reason is that these changes are being made by scientists, and the nurseries and websites aren't keeping up with the botanists in updating their sites, especially if they're still using "turkestanica" in their names. I believe that was replaced with "turkestaniana" some time ago, and even that is now a synonym of S. sclarea.

Well, in that case, I won't add any photo's. There are already so much pictures.