channel、slot和groove区别？

用户飞天狐

In order to cast through holes,blind holes,channels,slots and grooves as economically as possible, the figures given in table 6 and table 7 should be take into account.   在一铸造标准上关于铸造孔和槽的大小有这样一句话，我觉得channel、slot和groove的意思都是指沟槽，但不知具体有何差异，为什么要用这么多的词来表述。