Orange wood has a good sweet smoke that compliments beef, pork, chicken and fish. Eucalyptus is not good for barbecue, it has a high oil content and will ruin or even overpower the flavor of what you are grilling.
There's about 1000 species of eucalyptus, only a few are useful. You have to try out whatever eucalyptus you have - it might be good. Orange wood is excellent and gives good tasty smoke.
Orange wood is good as it gives a mild smoky flavor with a citrus undertone, good for all meats. But You should not use eucalyptus as when it burns it can become toxic.
