The France fullback left PSG for Barca over the summer.
He told Sport: "It's very different playing against Barcelona than the reverse... To take them on is very difficult and even more so at Camp Nou. You don't have the ball and when you do have it, they suffocate you and don't let you do anything.
"Barcelona is the biggest club in the world. We have to give everything to win the Champions League."
Digne added: "I liked Roberto Carlos. He was very good attacking and defending. I also like Philipp Lahm, who can play in the middle of the pitch and defence."