what is the difference between " for information please" , "for information and necessary action please"?

IN THE former case you need not to take any action but to circulate the memo for Information only .it means that whenever any action is needed to be taken ,you must keep that information in view .
In the later case the matter/case is submitted for information only but if the information contained therein is applicable upon,then act accordingly.
these types of files/papers go generally from the superintendent level to all juniors and the concerned branches which are likely to be effective sooner or later.

Necessary Action

Information is essentially the same as data - it is a collection of facts. It contains everything that is known about a topic, but on its own is not terribly useful. Knowledge is the useful product of information put together with a context in mind. Synthesizing the raw information into groupings and formats that make sense together - a flow chart showing troubleshooting steps, a spreadsheet of financial figures, a report showing which employees are paid over $35000/year in salary - creates knowledge. Edit: Neither of these on their own is Wisdom, which would be a third category. Wisdom is the retained knowledge and decision-making skills to use what is known and apply it to making choices in a context. E.g. A senior manager knows the what financial results imply for the company in the near future because he has studied previous reports, market publications, business admin theory, etc. A poker player folds his hand because he sees his opponent glancing repeatedly at the glass on the table (information) and interprets it as the one of his opponent's 'tells' (knowledge).

The first requires no action, even if necessary.

for information please is used to keep the concerned to be knowledgeable about the happenings though their intervention is not sought.

for information and necessary action please means that it is brought to their notice not only for their knowledge but also to intervene in the matter or use the authority bestowed upon them in solving the matter.

What happened in mexico two days back? ONLY FOR INFORMATION PLEASE. you just want to know for your GK.
What happened in mexico two days back? FOR INFORMATION AND NECESSARY ACTION PLEASE. you want to use this information in an action like you want to donate or you want to go there to help them...so on.
What happened in mexico two days back? you want to take necessary action about the accident.

Without information nobody can take necessary action. So, it is only a usage of saying officially.