前者有单复数之分，a garment (一件）衣服（尤指外套），garments 服装，衣服， 任何外衣 。
后者clothes没有单数，作主语时，谓语必须用复数，它可指上衣，裤子，内衣，外衣。但不能和具体的数字连用，只能和一些含糊数字连用 。
garment
1、Many of the garments have the customers 'name tags sewn into the linings.
这些衣服有很多内衬上缝有顾客的姓名签。
2、The garment is studded with pearls.
衣服上缀满了珠子。
3、China will host an exhibition of international garment machinery.
中国将主办国际服装机械展览会。
4、She left school to go to work as a dress model in the garment company.
她离开学校到服装公司当时装模特儿。
5、She disguised her true sex under a man's garment.
她穿着男人的衣服隐瞒自己的真实性别。
6、Simply scaling up a size 10 garment often leads to disaster
只是将10号衣服改大的话结果往往会很不理想。
7、The thicker the material, the less susceptible the garment will be to wet conditions
布料越厚实，衣服就越不容易浸湿。
8、She hired a garment.
她租了一件衣服。
9、The tailor carefully examined the cloth before starting to cut out the garment.
裁缝在裁剪衣服之前，仔细打量了这块布料。
clothes
1、Moira walked upstairs to change her clothes
莫伊拉上楼去换衣服。
2、He dressed quickly in casual clothes.
他很快穿上休闲装。
3、I have already started knitting baby clothes
我已经开始给宝宝织衣服了。
4、I also bought some casual clothes for the weekend.
我还买了些周末穿的休闲装。
5、She rested for a while, then had a wash and changed her clothes
她休息了一会儿，然后洗了洗，换了身衣服。
6、This clothes style is out of fashion.
这种衣服式样已经不兴了。
7、Our clothes were soaked with sweat.
我们的衣服给汗水湿透了。
8、He got his clothes dirty.
他把衣服弄脏了。
9、His torn clothes were soaked in blood.
他撕破的衣服被鲜血浸透了。