There is more nutrition in richer coloured vegetables than those of the same species with paler colour
For example a purple coloured cauliflower will have more nutrients than the white variety
Green leafy vegetables are very rich in chlorophyl and chlorophyl (sometimes described as the blood of plants)is very rich in magnesium and transforms into haemoglobin (rich in iron...and sometimes described as the blood of animals)
There are some plants that have toxins unsuitable for human consumption (such as green potatoes and the leaves of the Solanaceae family...potatoes, tomatoes, capsicum etc and others such as rhubarb) even beans have ingredients that need to be washed out or cooked out
So saying it is generally wiser to eat richly coloured vegetables thanless richly coloured ones
Remember too that fresh vegetables from your garden are much healthier than many fresh vegetables (days old ) from supermarkets
One of the most nutritious vegetables you can eat is Kale a brassica grown for its leaves and stems and very versatile in the kitchen...it has the advantage that it grows nearly all yera round in temperate climes
I am sure you will get much good advice on this topic here
cheers
Peter

I don't know about the tops of carrots, but I believe that the main problem with tomato or potato foliage is the alkaloids they contain. We generally do have some alkaloids (such as caffeine) in our foods or drinks, but I guess that potato and tomato foliage has lots of the really bad sort?!

I've read that iceberg lettuce doesn't have much going for it nutrition-wise, but that leaf lettuce is much much healthier, the darker the better. Sometimes they can be bitter.

Generally speaking, red and orange tomatoes have more lycopene and/or beta-carotene, which are the things most often cited in them as beneficial for cancer prevention. Yellow tomatoes don't have much of either, but can still be delicious. There's hundreds of other things in tomatoes as well (so I'm led to believe, but I don't know what they are).

PP

The green part of carrots is not poisonous but is bitter and not very palatable.
Green tomatoes contain glycoalkaloids as does the green (and also buds) on potatoes, so are best avoided.
I've put a link below that may be of interest to you. It's actually a vitamin company (which I don't know anything about) but the fruit and vegie information there is quite informative. (Scroll down on the page for the fruit and vegie part).
Cheers,
Dee.

Here is a link that might be useful: fruits and vegetables

More colour often means higher nutrient content with particular colours often indicative of the presence of particular nutrients:
red -> lycopene (or sometimes anthocyanin)
blue/purple -> anthocyanin
orange -> beta-carotene and carotenoids in general
green -> chlorophyll
white -> anthoxanthin
and many more. This is not always the case though. For example, many orange tomatoes are orange because of zeta-carotene which doesn't seem to have any nutritional value for humans.
These, and others, are often grouped together and called phytonutrients and often have anti-oxidant properties which are now all the rage nutritionally.
Personally, I think the best thing about richly coloured veggies is just that - their rich colours, which look so appealing on a plate and add to the pleasure of eating.

carrot tops are edible but not particularly palatable unless lost in a salad mix
Peter

Thanks for your replies. I thought it would be like that. One of the kids asked me once about different colours of the same type vegie and if they were all just as good for you. Now I can answer them. I've always preferred to have a big bowl of brightly coloured vegies instead of a bowl of one colour.

I think I will still be careful of any green tops of carrots because I know children and pregnant woman, especially, should avoid the green parts of potatoes and if they are similar, carrots should be avoided too.