Assalamu ‘Alaikum : السلام عليكم
when you meet a muslim
Translation: Peace be upon you
Wa’alaikum Assalam : وعليكم السلام
a Muslim greets you
Translation: And peace be upon you
Assalamu ‘alaikum wa rahmatullahi wa barakatuh : السلام عليكم ورحمة الله وبركاته
formal and great greeting to a Muslim
Translation: May the peace, mercy, and blessings of Allah be upon you
Wa’alaikum assalam wa rahmatullahi wa barakatuh : و عليكم السلام والرحمة الله وبركاته
a Muslim greets you
Translation: And peace and mercy and blessings of Allah be upon you