上(じょう)From the standpoint of

から言うと and 上 both indicate viewpoint, but から言うと introduces a subjective opinion from a specific angle, e.g. 学生の立場から言うと反対だ ('Speaking from a student's viewpoint, I'm against it'). 上 expresses evaluation based on a defined category, e.g. 法律上問題はない ('There's no problem in terms of the law').

上 and からすると・からすれば both indicate a perspective or basis for judgment, but differ in tone and scope. 上 is formal and often tied to institutional or thematic standpoints, as in 理論上の問題 (a problem from a theoretical standpoint). からすると・からすれば is more subjective and flexible, used with personal or situational cues, as in 表情からすると彼は怒っている (Judging from his expression, he’s angry).

上 and 上に share the same kanji but serve distinct functions. 上に adds reasons or qualities in a cumulative way, as in 綺麗な上に頭もいい (In addition to being pretty, she’s also smart). 上 by itself expresses viewpoint, as in 法律上の問題 (a problem from a legal standpoint). The former is additive, the latter indicates perspective. Both are relatively formal expressions.