sounds like /or looks like

Please give some situations where we cant use these phrases interchangeably.
sounds like /or looks like

Also which is more appropriate in the following case
Looks like she has big plans …
Sounds like she has big plans …

You can use them interchangeably when neither looking nor hearing are necessarily involved. The meaning is ‘I perceive that…’

Looks/Sounds like she has big plans– both are possible.

Mister Micawber,
In this semtence is the word - ‘like’ used as preposition or conjunction?
Please clarify me.

It is a conjunction; it is followed by a clause.