他在数学方面很难跟上其他同学,翻译中“跟上”翻译成keep up with 和catch up with 一样吗

不一样,keep up with的跟上一般是指在距离数量上的跟上,比如,走慢一点我跟不上你了.而且一般它都作为与某人保持联系来考察,如how many of old school friends do you keep up with?
在学习上的追赶用catch up with更准确.比如你给出的,he is hard to catch up with other students in mathematics.