May I know the meaning and difference between these two Hebrew words: Yhwh and Yhvh?

There is no difference, just regarding different customs of pronunciation the same Name. Regarding the meaning of that name, it's a long and complex answer. But just briefly, the Name of Y-H-V and H, is from the root: HVYH= existence, and includes that God always was (HYH), is (HVH) and will be (YHYH) forever. Also the Shadal, who was a linguist, points out that in most languages the term: "Yea" or "Yay" is a positive cry of happiness, while "Vei" (as in Oy Vei) is a negative cry of sadness. We recognize that all, both that which seems good as well as that which seems to us (at least meanwhile) as bad, it's all from the One and Only God, Who runs everything in the best way!