确实“和“实在”:
1.Both can be used as an adj. ,but the meaning of them is different.
"确实": as an adj. means 真实的,可靠的(actual and credible)=assured/undoubted.
ex. 这是条确实的消息。(This is an assured news) 确实 is used as an attributive adj.
ex.这条消息是确实的。(This news is undoubted ) 确实 is used as a predicative adj.
“实在”:as an adj. means 具体的,真实的(concrete and real)=actual
ex.你有没有实在的建议(Have you any concrete suggestions?)
ex.美丽不是实在的物体,但是桌子是。(Beauty is not concrete but a door is.)
note:In some Chinese localism,“实在”can be used to describe someone or something that is earnest and unfeigned.
ex.他很实在。(He is very earnest/unfeigned )他是个实在人。(He is an earnest person)
ex.他的话很实在。His words is very earnest/unfeigned)
Then, in terms of grammar when then are used as an adj.,实在 can be used to modify someone,but 确实 can't.
2.When they are used as an adv.,their meaning in Chinese are quite similar.
确实=certainly(it is used to indicate affirmative)
实在=really/quite(it is used to indicate degree)
ex.他确实是个好人。(Certainly he is a good guy.)
ex.水实在太多了。(The water is really too much)
note: in terms of Chinese gramma 确实 can be put in front of the sentence alone,but 实在 can't.
ex.确实,这太贵了。√ 这确实太贵了 √(Certainly,this is too expensive.)
我实在太累了。√(I am really tired.)
实在,我太累了。×
3.A familiar set-phrase about “实在” is "说实在的"(means "to be honest")。it is often used as a parentheses in terms of grammar
ex.说实在的,我很喜欢她。(To be honest,I love her very much.)
ex.说实在的,我不想去游泳。(To be honest,I don't want to go swimming )