I see, no wonder I was told someone into a buddha before
Shakyamuni Buddha
Buddha is someone who is not only awakened, but is able to lead
countless others to awakening. Such as Shakyamuni Buddha.
A pratyekabuddha is different. A pratyekabuddha is an awakened
being who lives in an era without Buddhas. He is unable to lead
masses of beings to awakening.
Lao Tzu is someone who doesn't want to teach, he just want to
retreat into the forest and live alone. He was stopped halfway by
an official who demanded him to write something down before he
leaves town into the wilderness (forever). Lao Tzu then wrote his
only written work - Tao Te Ching which consists of 81 verses.
Therefore, Lao Tzu is not a Buddha, at most a
pratyekabuddha.