The stress is different. "Анна" is stressed on the first syllable, "она" on the second. Also the н sound in "Анна" is a bit longer. Everybody mixes these up at first, including me, but if you find a sentence with each and listen a few times you'll notice a pretty big difference.
I've never heard a sentence with both words in it, so I can't compare the н sound. The stress is what I expected to be the difference. But I have just listened again to the recording of this sentence, and the emphasis is clearly on the first syllable. Aah-nuh. That's what has me confused.
I don't think Russian has a collective word for "grandchildren" - I think you have to say внуки и внучки. But if there is, I'd like to know it as well. :-)
Когда русский говорит "мои внуки", он подразумевает и девочек, и мальчиков. Потом, если надо, может уточнить - один внук и две внучки. Или - один мальчик и две девочки. А вот русского соответствия для Grandparents нет. Есть бабушка и дедушка.
Неправильное произношение. Ударение должно падать на первый слог - внУчка.
I literaly feel myself getting older just by listening to this sentence. Feels like I'm already sitting on some bench next to an old lady, watching the children play or something ... >.