Thursday 是星期四的意思，而Thursdays则是每个星期四的意思。

区别可以从以下例子看出：I will go to shopping on this Thursday, but my wife will do shopping Thursdays, as usually there are sale on that day. 我这星期四去购物，但我妻子通常每星期四去购物，因为那天通常有促销活动。

Thursday意为周四，thursdays意为连续几个周四。