Commonly, "家庭"means not only all of family members,but also the relations between family members, and the ecnomic level, culture level, even any thing and pets etc..So this word is wider than '家人'. By contrast, '家人' just means family members including parents, wife, son etc..They are different. For example, "家庭情况“ means the ecnomic level of family; '家庭组成‘ means who are in the family... If referring to members, the two words can use instead of eachother in some cases. But not all cases. For another example, ”家庭和睦“--although the phrase only refer to being members ,it doesn't be expressed as "家人和睦". But , a prince wanna marry a common girl, his "家庭" cannot agree, or his "家人" cannot agree!

家庭 vs 家人

Do both mean family members or is there a slight difference between them.

一般说来，“家庭”指的是家里所有的人以及这些人组成的关系，甚至包含家这个空间、总体经济水平、文化氛围等，以及物品、宠物等等，意义比较宽泛。但是“家人”的意思只有“家庭成员”，也就是父母、妻、子等人的因素。

家庭情况-家里总体经济水平如何、家庭组成——家里有什么人……

如果只包含家里的所有人，有的情况下是可以混用的，但也不是所有情况，比如说家庭和睦——虽然只有人的因素，但一般不说家人和睦。反之，对于贵族的儿子娶个平民，家庭是不会同意的——也可以说家人是不会同意的。