“星期”即星的日期。用日、月、土、火、水、木、金七个星期的名字命名一周中的每一天，所以一周又叫一“星期”。 “礼拜”是基督教会的一种宗教仪式，教会把星期日定为教徒对上帝礼拜的日子，这一天也就被称为“礼拜”天。一个星期就相应地称为一个“礼拜”了。后来，欧洲传教士把基督教传入我国，我国人民也有称“星期”为“礼拜”的习惯了。

As far as I know the meaning is the same, however in Taiwan "libai" is more commonly used.

Don't feel confused. They are basically the same.^_^

when we say some days of week, "xing qi" is the same as "li bai", both of them are the meaning of "week". we can say "礼拜三" or "星期三", they both mean "Wednesday“. But "li bai" have the meaning of “weekend", like "又要过礼拜了", but we cant say "又要过星期了".

They both have the same meaning in chinese expression, but the cultural origins are different, "xingqi" is the expression based on chinese culture, while "libai" based on the western cultural,it seems that "xingqi" is more former than "libai" in china.