Center, focus, centralize, concentrate are comparable (though not closely synonymous) because all mean to draw to or fix upon a center.
Center strongly implies a point upon which things turn or depend; typically the term is followed by a prepositional phrase (as with in, on, or upon) that names the thing (or sometimes the person) upon which all responsibility or all attention is placed or around which anything or everything of a specified kind (as hopes, fears, or joys) turns.
Focus implies a point at which a number and usually the total number of things of the same sort (as rays of light, waves of sound, attentions, or interests) converge and become one.
Centralize is used of things (as government, authority, or administrative procedure) that may be either gathered about a center or divided, distributed, or diffused; it especially implies the placing of power and authority under one head or in one central organization or the bringing together of similar things at one point.
Concentrate differs from the other words not only in being more widely applicable but also in its greater emphasis upon human skill and human methods, discipline, or effort in effecting its purpose; the word may be used not only with reference to what may be centralized or focused and to much that may be centered but is applicable also to material substances that can be reduced in volume (as by dehydration or evaporation), thereby gaining in strength or intensity (see also COMPACT).