Two-year degrees in the US often award either an "associates degree" or some technical certification/profession-specific degree.

These degrees are *not* typically part of the "bachelors -> masters -> PhD" pipeline or more generic "bachelors -> professional degree".

Some students may start taking courses at a 2-year school and then *transfer* to a 4-year school (with or without actually completing a 2-year degree, and hoping to have as many of their 2-year credits count/transfer towards their 4-year degree), because 2-year schools are both less expensive and less selective. 2-year programs rarely have any sort of on-site housing ("dorms") and limited "student life" opportunities (clubs, social facilities, athletics).

Not all 2-year schools are appropriate for this track. Some are specifically designed as technical degrees to get students into a specific career, and do not provide the "general education" credits (basic math, science, social studies courses) that are useful for transferring to a 4-year program.

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If you wanted a MSc in the US, starting from high school you would either:

A) Enroll at a 4-year program, and then

B) Apply to Masters programs*


or 

A) Enroll in a 2-year program,

B) Transfer to a 4-year program (bringing with you some or all of the credits you already earned), and then

C) Apply to Masters programs*

If you plan for the "ABC" pipeline it is definitely worth exploring the requirements of the 4-year institution(s) you plan to attend so that you know which courses you take will transfer. Most students who would follow this path instead of the "AB" path would be doing so either for financial reasons or because the student does not feel academically prepared for a 4-year school (the quality of high school education varies quite a bit in the US, and even a very good student at a disadvantaged high school might have trouble with the jump to a 4-year school).

There is no particular advantage to completing a 2-year degree program before starting a fresh 4-year degree.

(* - it's possible, though not particularly common in the US, that you enroll directly for a combined bachelors+masters program)