later and in

With a time expression, we generally use later to mean ‘after that time’, and in to mean ‘after now’. Compare:

• She got married on her 18th birthday; six months later she was divorced.
• Penny’s coming on July 1st, and Tom will arrive about a week later.
• I’ll see you in a few days. (not I’ll see you a few days later.)

But without a time expression, later can be used to mean ‘after now’.

• Bye! See you later!