Nice picture. I don't know photography, but is natural light better than flash? Is it harder to achieve?
Nice looking couple.
Better is in the eye of the beholder- but if you're trying to achieve a specific result, the more control you have of the light, the better. For instance, in this picture, with control of the light, you have more of a chance to get the black jacket with texture and detail and not have the blown highlights in the bride's hair and both their noses. You could also tone down the shadow between them, making them less "separated" (though having them both looking in the same direction would probably be enough in the case of the first picture.) You'd also be able to set up a background light and not have the off-color background and noise, or overpower ambient behind them for the same result.
In the second picture, you'd be able to open the bride's face up, so that she's also a subject instead of a background element, not side-lit (which is very unflattering for women's skin, as you can see) and you could again get rid of the noise/color in the back- but again that depends heavily on what result you're trying to achieve.
In both cases, with control of the light, you'd have more posing options, so the bride wouldn't be a hunchback in the first shot and almost showing too much cleavage in the second- because when you can move the lights, you're not at the mercy of the angle and direction of the sun and where the windows are at.
The only other thing I'd mention, since the OP seems open to critique is that I'd definitely whiten the bride's teeth in the first shot before she saw it, and I'd probably also clean up and de-redden their eyes too.
"Harder" depends a lot on the set-up, timing and work...
wheelhot said:
Well to me, natural light is of course better then flash because if you do it wrong, flash could give a bad effect to your picture.
Doing anything wrong could ruin the picture- I've seen more bad pictures of people in natural light than flash ones- in fact getting the light, subjects and shadows right with natural light doesn't happen very often- you need a compelling subject much more frequently with natural light than you do with flash. However, doing flash "wrong" is really difficult if you have the right equipment and spend time learning how to use it.