Patricia, there are many. Kootenay has more clusters. The flowers open (if they open, both are given to terrible balling and bud-rot) with a Malmaison heart which turns yellow. Its buds often have big red streaks on the outside (see my photo from last winter) which Kaiserin never shows. The buds and flowers of Kootenay are often so much of a mess that you can't see which way they face. When you can see, they face close to up. Kootenay has not much scent.
Kaiserin is often disfigured by balling, but less than Kootenay. All the non-white shading of the flower and bud is apple green. When first the sepals fall back from the bud it shows as pure apple green all over, like dyed silk (see this photo). The shading of the open flower begins pale green and in hot weather turns cream (see photo), not yellow. The flowers nearly always face sideways or down (compare Kootenay). Finally, any open flower has detectable scent, usually a strong scent which to my nose is pure Tea — it lacks the woody notes of a typical Hybrid Tea — stronger though less sweet than that of Mrs Herbert Stevens nearby. I'd say its scent is in the top 20 known to me.