"Nothing is as dangerous as an ignorant friend; a wise enemy is to be preferred.” -Jean de la Fontaine
"A human being is not attaining his full heights until he is educated." -Horace Mann
I like to differentiate between these two, because I think 'ignorant' is a bit of a loaded word. I don't like calling someone who simply hasn't seen these terms before 'ignorant', they just aren't aware of it yet and haven't had a chance to learn, even if it is technically accurate. To walk into a strange new world and immediately be called 'ignorant' for being new might be hurtful and make them less willing to learn. Considering what I deal with a lot of the time- closing people's minds is not a good thing.
I think of ignorance more in terms of 'willful ignorance'. You've tried explaining it to them, but they refuse to get it. My mother is a prime example of this- I've probably come out to her about 5 times, and I'm still not convinced she knows I'm transgendered because she ignores anything she doesn't like. Ignorant people are often impossible to deal with, because even if they've been exposed to the information they ignore it. I've dealt with too many of these people, and it's probably why I rely on links rather than actually telling people in my own words- if the person has a problem with the link, they can take it up with the webmaster and I didn't waste any energy on them.
Uninformed people, however, aren't so bad. A few times I've had the pleasure of being the first person to introduce someone to a concept, such as transgenderism, correct any misunderstandings, and see them accept it fairly easily. Because of this, I don't think people who simply aren't aware of an issue should be automatically labeled 'ignorant', since sometimes when they find out about it they genuinely want to know and understand.
It's not always easy to tell one from the other, and an ignorant person can be uninformed, and it's easy to understand not wanting to waste your time trying to educate anyone when so many will just ignore what you're saying- but either way I'd rather not assume all uninformed people are ignorant, when many of them may become our allies.