Letter vs. Email

Beginning:

In Email: You have fill in this before say "Hi...." (or you can use "Dear", no prob here)
From
To
Subject
In Letter: You have to write this structure above the sentence "Dear..." (never say "Hi", please ^^)
Street
City/Province
Country
Date

Something you want to send with your mail

In Email: You say ATTACH
In Letter: You say ENCLOSE

Ending (often use - not obligatory)
In Email: Looking forward to hearing from you
(Give my) love to...
Love (from)
In Letter: Hope to hear from you soon.
(Give my) regards
Best wishes

Bonus: The structure of an informal letter/email to your friend (far away from you, maybe in foreign country)

Beginnings
- Dear/Hi + Name
- Sorry for not writing earlier but...
- Thank you/Thanks for ....
- It was great to hear from you...

Main Content
.....................

Endings

That's all for now
Hope to hear from you soon/Looking forward to hearing from you
(Give my) regards/ love to...
Best wishes/ Love (from)

PS
...................

Tell me what do you think about this issue? As soon as possible. Thanks