A vanishing cabinet can take you to a place where Apparation/Disapparation is not possible (eg. Hogwarts). Malfoy used it to help Death Eaters to get into the castle undetected.
From "Harry Potter and Half-blood Prince" , chapter The Lightning-Struck Tower
Malfoy looked as though he was fighting down the urge to shout, or to vomit. He gulped and took several deep breaths, glaring at Dumbledore, his wand pointing directly at the latter’s heart. Then, as though he could not help himself, he said, “I had to mend that broken Vanishing Cabinet that no one’s used for years. The one Montague got lost in last year.”
“Aaaah.” Dumbledore’s sigh was half a groan. He closed his eyes for a moment. “That was clever. … There is a pair, I take it?”
“In Borgin and Burkes,” said Malfoy, “and they make a kind of passage between them. Montague told me that when he was stuck in the Hogwarts one, he was trapped in limbo but sometimes he could hear what was going on at school, and sometimes what was going on in the shop, as if the cabinet was traveling between them, but he couldn’t make anyone hear him. … In the end, he managed to Apparate out, even though he’d never passed his test. He nearly died doing it. Everyone thought it was a really good story, but I was the only one who realized what it meant — even Borgin didn’t know — I was the one who realized there could be a way into Hogwarts through the cabinets if I fixed the broken one.”
“Very good,” murmured Dumbledore. “So the Death Eaters were able to pass from Borgin and Burkes into the school to help you. … A clever plan, a very clever plan … and, as you say, right under my nose.”