what is the difference between 覆盆子 and 树莓?
Check wiki, basicly 覆盆子(Rubus idaeus) is one kind of 树莓(Raspberry), 树莓(Raspberry) also include 山莓 （Rubus corchorifolius）, 牛叠肚 (Rubus crataegifolius) etc.

树莓英文为“Raspberry”也可以指覆盆子（Rubus idaeus）但是它只是其中一种，广义来讲还可指悬钩子属内的部分物种。