Help me with this, please!

[hashoomer]

need help in explaining the difference in the meaning of the following:

a Give me a hand with this bag, will you?

b Could you give me a hand with this bag, please?

And how would i teach this?.

[rewboss]

The first is very informal, and often implies that the speaker is getting a little impatient. It's an order, and the added tag question "will you?" is added to orders to indicate frustration.

The second is much more polite. It is a request, beginning with "could you", which is standard for formal, polite requests, and ends with "please" to make it even more polite.

[buggles]

In my experience, the first is how I would ask for help from someone I know, like a friend or relative. Usually it's a straightforward request for help and doesn't always imply impatience-it depends on the tone of voice used.
The second is how I would ask for help from a stranger, but like most English people I'd probably crick my back before asking a stranger for assistance!