If you are NOT that confident in your picture taking, and really need to impress - I suggest shooting in RAW as this will allow you to rescue your photos in greater detail such as making white balance & exposure adjustments to your images while still retaining good quality. You can still do this in JPEG but when you make these adjustments, you will lose a LOT of quality and you'll most likely end up clipping highlights, and shadows.
Sure, you could adjust the white balance setting manually and start shooting in JPEG, but if you are shooting in a dynamic enviornment such as the outdoors, there are plenty of factors that affect white balance calculations, and you can never really "set & forget".
For instance, white balance can change if:
* you are shooting someone in the shade on a sunny day as opposed to direct sunlight
* the hours of the day tick by, the sun raises / sets and this changes the colour temperature of the sky
* clouds may cover the sun from time to time, and this will also affect white balance.
The only time i'd set white balance in the camera and trust it, if I were shooting under controlled lighting conditions such as a fashion parade (though even then the light changes between each show).
Basically, if you are shooting for an important event, shoot in RAW.
To answer your question, "What's the difference between RAW & JPG", if you did a Google search on this, you would get quite a lot of information on this comparison, but my own summation of the differences between JPG & RAW is:
RAW is considered a 'digital negative' in the world of digital photography. A RAW file basically captures an image taken straight from the camera's sensor before ANY in-camera settings are cemented. I say 'cemented' because in-camera settings are still applied to the RAW file when you view it, but you can make these changes if you don't like what you see, like exposure, white balance, sharpening, tonal ranges and basically anything else which your camera is able to adjust, you can adjust it yourself AFTER you take the shot, without effecting the original quality of the image.
When your camera takes a JPEG image, your camera still captures an image as a RAW file, but it then applies in-camera settings like exposure, whitebalance, etc. to the image and churns this out as a JPEG. When images arrive in the form of a JPEG, it is arriving in a form where the image has already been manipulated, so if you then start manipulating this image, you are essentially manipulating a manipulated image - whereas with RAW, you are manipulating the image directly and the new settings you apply are as though the camera took that shot originally.
Also, keep in mind that JPEG is a 'lossy' picture format so it knocks out a lot of colour information from your photos, whereas RAW retains all the detail.
Perform this exercise yourself, take the same picture, one with RAW & one with JPEG and then make adjustments with both, you'll easily see the difference when you start adjusting exposure alone.
So why bother with JPEG? I (personally) use JPEG when shooting under controlled lighting conditions, and needed to send the pictures within 20-40 minutes after taking the shot to the newspaper or magazines - it saves a lot of time having to post-process your images and if you have time deadlines to meet, you simply don't have the time to mess around with RAW so you need to get your camera settings right to begin with before the shoot so you can churn out beautiful JPEG's that have been setup correctly.
Some cameras have the ability to shoot RAW + JPEG simultaneously, try this out so you can see the difference. Sometimes you (or your camera if your shooting auto) may get the settings right and would churn out nice JPEG's, other times you may not (under / over exposure, white balance, sharpness, etc.) and this is where RAW saves the day.
Having said all this, if you are reasonably experienced with your camera and picture taking in the beach enviornment, shoot in JPEG. A final tip: if you don't intend on printing these photos larger than a 6 x 4 inch print or to show people on the PC monitor, and won't be doing a lot of cropping, don't shoot large JPEG's, shoot smaller sized JPEG's that fit your purpose and you'll be able to fit a lot more onto the card if you're stuck for space.
Good luck!