Unfortunately, I have to tell you that Vietnam doesn't have any department stores that are at the same level of JCPenny, Macys, Dillard's, Best Buy, etc. However, there are department stores such as Vincom and Parkson that have Levi's, Dr. Martens, Nine West, Mango, Versace, Emperio Armani, Converse, Charles and Keith, etc. And you can find more luxurious fashion stores located at the center of Ho Chi Minh City such as Guess, Gucci, Gap, Louis Vuiton, Coach, etc.
By the way, Forever 21, H&M, Hollister, A&F, Aeropostale, American Eagles have not come to Vietnam yet.
For electronic products, you can come to Nguyen Kim, Phong Vu or Wonder Buy in Ho Chi Minh City. Those are the largest electronic stores in Vietnam that have almost all of the famous brands with various types of products from laptops, digital cameras, to game players, usb and such.
Well, overall, if you wanna shop for branded products, Vietnam cannot be compared to NYC absolutely. But if you wanna shop for nice good looking outfits with cheaper prices, you can find a lot of them in Vietnam.
Hope my info is useful.