Why does one have to be "good" for these not to be the same? Those things are different, with different motivations, methods, outcomes, etc.
And all in all, forms of colonialism during antiquity hadn't nearly the negative impact on the colonialized areas and people as modern, imperialistic colonialism.
Or do you really think that phoenician (antiquity) or norse (early medieval) trading outposts that integrated into the surrounding cultures and sometimes organically (!) evolve into a new culture (for example, Carthage, Kievan Rus) or viking/norse settlements in what became a french vassal in Normandy is the same as european powers carving up Africa among each other, comitting genocide in the process and drawing new borders disregarding tribal territories?