Are boys emotionally different than girls?
This question can not stand unqualified. What age range? Brought up where?, by whom?, how? Are they brought up by the same parent(s) with the exact same methods?
But even given that all the conditions and environmental factors are equal, there is no doubt that emotional development of boys and girls is different, however.
Even if you raise boys and girls in an exactly identical manner (which is extremely rare, but some cases have been documented), certain built-in hereditary or genetic tendencies still tend to predominate in each group.
Emotional development, including empathy, however - are to a great extent the results of social conditioning.
But it would be a mistake to assume that girls would ALWAYS turn out "softer" or "more considerate", or that boys would naturally be "more industrious" or "boisterous".
All this depends greatly on the environment and upbringing methods. And while it's clear that differences between the sexes exist on emotional and physical levels, right from the early childhood, those can be shaped and modulated by the upbringing as well as the environment.
Interestingly, many "properly brought up" boys and girls (whatever that means) often display very similar emotional characteristics, with boys frequently being far more "sensitive" - up to a certain age.