Oneself and myself means the same thing?
No.
Well, only if you're a monarch.
Consider the statement: "one can do it oneself".
"One" in this instance is roughly synonymous with "a person" (in general - i.e. a non-specific individual).
When you use "one" you would use "oneself"
If you used "a person", however, then you would say "a person can do it themself".
If you were referring specifically to yourself then you would say "I can do it myself".
If you were referring specifically to the person you're talking to you would say "you can do it yourself" etc.
The only time "oneself" is synonymous with "myself" is when using "one" to refer yourself, but this is usually only done by monarchs (Queen Elizabeth II uses it).
For example, Queen Victoria is famous for saying "One is not amused" when referring to herself.
There may be a few people who consider themselves in the upper echelons of society that use it, but it is pretentious if you're not actual royalty.
I find it is almost as bad as people referring to themself in the third person, such as when Trump says "Trump is going to do this!"