Complex sentence: TMG is related to choline (trimethylaminoethanol), with the difference that the terminal carboxylic acid group of trimethylglycine has been reduced to a hydroxyl group in choline.
Split into simpler sentences: TMG is related to choline (trimethylaminoethanol). The difference between the two is that the terminal carboxylic acid group of trimethylglycine has been reduced to a hydroxyl group in choline.