Unless you grow them side-by-side, you won't know there is a difference between them. 'Regal Mist' is simply another cultivar of the species, and is a little smaller than the species. I can't tell any difference in bloom or foliage color, but I prefer 'Regal Mist' because it is a bit smaller, and easier to fit in my relatively small garden.

Donn Thanks for your reply. I am a little confused because of the descriptions on the tags of these two grasses at the nursery. They are both from Monrovia nurseries. Please look at the url I have listed and click on the different grasses to show the write up of the plants concerning the height of each. The Monrovia tag says the Regal Mist is 4' high in bloom and the plain Pink Muhly says it is 3' high in bloom. Is this correct or have you found it to be the other way around (per your post). I have a smaller garden myself and would prefer the smaller of the two grasses. Thank you so much for taking the time to help me.

Here is a link that might be useful: Monrovia Descriptions of Pink Muhly and Regal Mist P.M.

'Regal Mist' didn't reach 3' (foliage) in my garden, but species Muhly was three and a half feet. In flower, they each added another foot.

'Regal Mist' was also more compact in habit, and didn't flop as much as species.

Another factor which may have affected these results is that I grew the species Muhly from seed, while the 'Regal Mist' was purchased as plugs.