I came to this realization while attempting to draw a caricature of Britney; she looks like Liza Minnelli, or, well, Britney's cartoon-self looks a lot like Liza Minnelli. In real life, they share a few features and only sorta vaguely resemble each other. I know saying this won't please my fellow fans; they much prefer that we only compare Britney to more conventionally glamorous women that look nothing like Britney Spears, like, um, Marilyn. They'd probably jump with delight if I said Britney looks like Liza's mother, Judy, but that simply isn't true, either. Britney shares more of her features with Liza. Britney is certainly prettier than Liza, whose features are decidedly less delicate than Britney's, but I think there's a similarity in the way their eyes are shaped and downwardly-slanted, as well as the overall shape and bridge widths of their noses. I can't begin to count the number of times I've attempted to draw cartoony Britney and ended up changing my doodle into a picture of cartoony Liza.
Here's a fabulous example from
Pretty On The Outside:
Because it's necessary to exaggerate Britney's features for the purpose of creating a caricature, she always ends up looking like some fairly close relation to Liza.
Pressed souls 
I always mix them up.
