Careful, meticulous, scrupulous, punctilious, punctual are comparable in their basic sense of showing or revealing close attention to details or care in execution or performance.
Careful implies great concern for the persons or things in one's charge or for the way in which one's duties or tasks are performed. With regard to the former, the term implies solicitude or watchfulness and with regard to the latter, it usually implies painstaking efforts, thoroughness, cautiousness in avoiding errors, and a desire for perfection.
All of the other words mean exceedingly careful, but they vary in their implications of the motives which inspire such carefulness and, to a less extent, in regard to the objects of attention.
Meticulous usually suggests timorousness lest one make the slightest error or fall short of a high standard; in addition, it implies extreme fussiness or fastidiousness in attention to details.
Scrupulous (see also UPRIGHT) implies the promptings of conscience, not only of one's moral conscience but of one's sense of what is right and wrong (as in fact, in logic, or in aesthetics); it therefore also implies strict or painstaking adherence to what one knows to be true, correct, or exact.
Punctilious, on the other hand, implies knowledge of the fine points (as of law, etiquette, ceremony, or morality) and usually connotes excessive or obvious attention to the details or minutiae of these.
Punctual may occasionally come close to punctilious in its stress on attention to the fine points of a law or code, but in such use the term carries a much stronger implication than punctilious of emphasis on their observance and a weaker implication of concentration upon the minutiae.
More usually the term implies near perfection in one's adherence to appointed times for engagements or in following a schedule and then means punctiliously prompt.