Lohan was on a soap. That's all I need to know.
For anyone too lazy to click and scroll on Aaron's link, here it is...
Hilary Duff vs. Lindsay Lohan
This feud kicked off when Duff started dating Lohan's ex, Aaron Carter. Then Duff showed up at Lohan's Freaky Friday premiere, some say to intentionally upset her. Things really got heated when Duff realized Lohan was at the premiere party for Cheaper By the Dozen. Her mom went to Universal executives to have Lohan kicked out, but the execs said she was an invited guest and she could stay. This feud may go back even farther as both were up for many of the same roles while at Disney.
Anyways, my $0.02
At first, both were okay. They were those "Aw, what cute kids" actors. Lohan was on a soap (Another World as Alli Fowler), Duff had that Casper movie. Then, of course, they grew up. Duff became the plastic prepackaged blonde teen idol that all little girls wanted to be and all teenage boys wanted to do. Lohan became...well, the same thing, except she was more "rough around the edges", so to speak. She was more...grungy, I guess, while Duff was still trying to be a 12 year old and a 17 year old at the same time to appease little girls and teenage boys, respectively.
After they grew up, I found Duff to be extremely annoying, with a nasal singing voice, and couldn't even enjoy the early episodes of Lizzie McGuire when she wasn't such a pop princess. Lohan won my approval by default (although it can be argued that I favor her because of her soap opera roots).
I absolutely refuse to even try to watch Duff's new movies (Cinderella Story would have been too teenybopper for me anyway regardless if she was in the role or not), and I'm a bit selective of Lohan's (Drama Queen just looked rather boring to me, but my mom's a big Lohan fan so we may end up renting it), but I'd prefer having Lohan on my screen rather than Duff.
Also, a bit more gossip about Duff/Lohan: (not sure which is true and which isn't, as it's all gossip)
Aaron Carter had been going out with Lohan, then started going out with Duff, then dumped Lohan, continued with Duff.
At the CBTD premiere, Duff did try and get Lohan to leave, so Lohan did leave, just to be the bigger person.
Lohan sometimes ends public appearances with an "I Love You, Hilary!" to try and make peace (so if this is true, they're still at odds with each other?).
To my knowledge, the "Lindsay Lohan takes Duff's rejected roles" thing only applies to
Confessions of a Teenage Drama Queen. But I'm sure every other role Lohan will get will be called a Duff-Rejection by some fanatic Duff fans, solely to discredit Lohan.
Did I also mention that Lohan was on a soap?
Escapay