They have the same meaning, but 'breatfeed' would be used. "It is best to breastfeed newly born infants, rather than bottle-feed" 'Nursed', when used with 'baby' or 'child' is also acceptable. "She is nursing her baby." "Suck at the breast" would be unnacceptable in any normal conversation. It would be considered awkward at best and rude at worst.

虽然 breast feed 和 nurse 是相同的意思但用法有一点儿不同。尽管这两个词常可互换，可是照我的看法，谈到一位特定的人我们常说 nurse (She is still nursing her child.), 然而 谈到那个行为我们常 用breast-feeding, (Were her children breast-fed or bottle-fed - 他的孩子喂是人奶还是牛奶。) 还有另外一个词， suckle, 意思也是哺乳。虽然 这个词适用于人和动物，(She has a hard time[ has difficulty] suckling her baby. - 她艰难地哺育孩子) 说到动物是常常用的。 Suck 的意思是 to draw liquid into the mouth (to suck on a straw), 还是 to draw nourishment, to suckle. 虽然可以表示breast-feed的意思, 但是因为也表示一种性行为的意思有人难以启齿.

We use breastfeed.