JD (Juris Doctor) is the first law degree, it is a general degree with three years' study, which is after university (the students must first finish their university and then they may apply for JD).
Students with ben ke from China are able to apply for JD by taking the LSAT. The only way to join a JD program is to pass the LSAT. Toefl is required, but only by some law schools. Any major is ok for JD, and students with less common majors are likely to be very attractive to the application committee.
After getting a JD (from an ABA-approved law school), the students can take the bar exam in any state they wish. These students can be US lawyers anywhere they want, and also, under Chinese law, Chinese citizens can take the Chinese exam and become Chinese lawyers.
LLM is a masters degree in law, and is usually for students with a university degree in law, or students who are already practicing lawyers. The LLM has no entrance exam, however the TOEFL is almost always required for Chinese students. The LLM is generally one year, and will not permit the student to become a US lawyer in any state. However, New York and California currently permit LLM students to apply to take the lawyer's exam with some conditions.
While the LLM works better for many students, the JD has some clear advantages. The JD study trains young lawyers thoroughly in legal thinking, and so law firms will look more favorably on JD holders in general. While many LLM graduates can find good jobs, the value of the LLM itself is not so high. If the LLM holder has good skills prior to getting the LLM, then they may be able to secure a good position. But the LLM, by itself, cannot be seen as changing the skill set of the lawyer so drastically.
The Law School Admission Test (LSAT) is not required for admission to LLM programs in the US. A first degree in law is required for admission to LLM programs. Many US states limit the eligibility of LLM-degree graduates to sit for the bar examination if their first degree in law was earned outside of the US.