The Distinction Between Offer Acceptance and Invitation

Maine aap sabko question puch raha hoon, kyunki mujhe lagta hai ki mera professor galat baat keh raha hai. Woh kaha ki invitation ko bhi offer ke hi saman par rakhna chahiye, lekin phir yeh kaise ho jaata hai ki parties ke beech contract banega? Aur kya invitation par se agreement to nahi ho jaata? Mera textbook keh raha hai ki offer aur acceptance ke beech ek legal relationship hota hai, lekin invitation par se koi legal relationship nahi hota. Lekin fir woh yeh bhi kaha ki koi bhi offer ko accept karna ek formality hai, aur invitation par se bhi accept ho sakta hai.