The biggest difference between factual behavior and legal behavior is that factual behavior has no requirement on whether the subject should have the capacity to act. The subject of a legal act should have corresponding capacity, otherwise the act cannot be established or take effect. For example, a 5-year-old child found the lost property and managed it for no reason. Five years old is a person without civil capacity in civil law, but negotiorum gestio still holds. The negotiorum gestio here does not require the subject to have civil capacity. On the contrary, if a 5-year-old child abandons or gives away the jewels in his family, it is a legal act, and the actors such as abandonment and gift must have the capacity to act, otherwise it will be invalid.

A citizen made a will before his death, without civil capacity, and the will made was invalid, so it is required that the subject have corresponding capacity, that is, legal act.

B. It is obviously necessary for Party A and Party B to sign a sales contract, otherwise, the validity of the contract may be uncertain or invalid, which is a legal act.

C Party C's damage to Ding Jia Cai Dian is a typical factual act, which does not require the conditions of legal capacity.

D young men and women who want to register their marriage in the marriage registry must have qualification requirements.

Of course, in addition to the above differences, there are others, such as: whether it is based on human will, etc. I believe you can master the biggest difference and take more than enough measures to take the exam.