I believe there are girls who are both at once. I also based this on how the look most of the time, since when dressed a certain why one can go from cute to sexy and vice versa. Sorry about no links, I do not have that much time to go through and find a pic or two, plus typing or copying the name into Google will do and you will see more pictures of them there. You should know most of the people already anyway.
Sexy: Amanda Heard, Blake Lively, Demi Lovato, Dita Von Teese, Elizabeth Gillies, Erin Andrews, Eva Mendes, Hayden Panettiere, Holly Willoughby, Katy Perry, Jessica Lowndes, Jessica Simpson, Kat Dennings, Kate Upton, Kim Novak, Kelly Brook, Marilyn Monroe, Rita Hayworth, Sofia Vergara, Yvonne Strahovski
Cute: Alia Bhatt, Carly Rae Jespen, Caroline Sunshine, Ellen Page, Emma Watson, Jennette McCurdy, Lindsey Stirling, Mary Pickford, Miranda Cosgrove, Reese Witherspoon Sarah Hyland, Stefanie Scott, Zooey Deschannel
Both: Alex Morgan, Amy Adams, Ariana Grande, Dianna Argon, Frankie Sandford, Hayley Williams, Jennifer Lawrence, Jessica Alba, Julie Bowen, Kate Middleton, Karen Gillian , Katharine Mcphee, Katharine Jenkins, Lea Michele, Leighton Meester, Mila Kunis, Taylor Swift, Viven Leigh