Lǐlùnjiā hé shíjiànzhě de shìjiǎo wǎngwǎng bùtóng.
Theorists and practitioners often have different perspectives.
Tips
grammar
家 (jiā) here is the agent suffix for 'expert / professional' — same suffix in 科学家 (kēxuéjiā, 'scientist'), 艺术家 (yìshùjiā, 'artist'), 作家 (zuòjiā, 'writer'), 音乐家 (yīnyuèjiā, 'musician'). It originally meant 'house/family'; here it metaphorically means 'someone whose house is X-discipline'.
register
Slightly formal — written rather than colloquial. Sometimes used with a faintly pejorative edge, like English 'armchair theorist', when contrasted with 实干家 (shígānjiā, 'doer / pragmatist').
