Both ἄλλος and ἕτερος are translated in the A.V. by ‘other' and ‘another;' but their signification is not the same, and in some passages there is a marked difference. ἅλλος is ‘another' or ‘others' numerically: an officer says to one soldier, "Go, and he goeth; and to another, Come, and he cometh." Matt. 8:9,
On the other hand, ἕτερος expresses ‘a different kind.' John sent his disciples to ask the Lord if He was the coming one, or were they to look for a different one? Was He the One prophesied of in the O. T. Matt. 11:3? Christ is a priest of a different order, and came of a different tribe from Levi. Heb. 7:11, 13, 15. In Egypt there arose a different king that knew not Joseph, Acts 7:18: doubtless referring to one of a different dynasty. See also chap. 8:34.
Both words occur in Gal. 1:6, 7: Paul wondered that the Galatians were so quickly changing to a different (ἕτ.) gospel, which was not another (ἄλ.). Lest it should be supposed that Paul was admitting that there could really be another gospel than that he had preached to them, he uses ἄλλος with an emphatic negative, "which is not another." It is the absolute assertion that there was no other, nor could be: cf. also 2 Cor. 11:4.