What is the difference in terms of responsibility between instructions or directives given verbally (orally) and those given in writing?

instead of telling verbally , make a monthly task plan in excel sheet and  if needed make a meeting and minute it with target date

One is kind of ok to give, and needs to be captured mentally.The other one gets documented

oral nor full responsibility and may be forget and make big losing to co.

written is the best to be fair with all and be a reference if we faces and problem