おはよう (ohayō) means “good morning”

More examples

友だちにおはようと言います。tomo da chi ni o ha yō to i i ma su

I say "good morning" to my friend.

先生におはようとあいさつします。sen sei ni o ha yō to a i sa tsu shi ma su

I say good morning to my teacher.

Marks a casual morning greeting that acknowledges the start of the day.

おはようございますohayōgozaimasu: A polite morning greeting used in formal or respectful conversation.

朝、人と顔を合わせた際に用いるあいさつの言葉。asa hito to kao o a wa se ta sai ni mochi i ru a i sa tsu no koto ba

おはよう (ohayō) comes from お早く (ohayaku, "early"), in which お (o) is a polite prefix and 早く (hayaku, "early") means "early."

おはよう (ohayō) is casual, while おはようございます (ohayō gozaimasu) is the more polite form used in formal conversation.