What is the difference between 演奏 and 表演?
表演 is a general term for 'perform (v)' or 'performance (n)'; 演奏 is a specific term for 'perform playing a musical instrument(v)' or 'musical instrument playing performance(n)'

You can 表演 (perform) any kind of performance and any performance (表演) can be performed

Example: 胸口碎大石，高空踏鋼線，肚皮舞，單手打蛋，倒掛金勾射球，書法，騎射 and so on

演奏 (n) =  (musical instrument) playing performance; 演奏 (v) = perform playing (musical instrument)

Example:
(v) 演奏小提琴，演奏鋼琴，演奏二胡
(n) 小提琴演奏，鋼琴演奏，二胡演奏

演唱 (v): perform singing; (n): singing performance

Technically, playing piano and singing song (表演彈鋼琴; 表演唱歌) is 表演 too, but they have their own dedicated words 演奏 and 演唱, therefore, 表演 is not used for musical instrument performance or singing performance.
No one says 表演'陽關三疊' (name of the music), only 演奏'陽關三疊''; No one says 表演'明月千里寄相思' (name of the song), only 演唱'明月千里寄相思'
演出 (v): 'perform'/ (n):'show' is mostly for stage-play or opera. e.g. 演出舞台劇; 演出歌劇