What's the difference between 操练 and 训练?
操练 -  practice; drill; train
训练 - train; learn
操练 mostly refers to performing a set routine repeatedly and prolongedly
训练 is a more general term for 'to train'.  While  操练(drill) can be a part of one's 训练(training), it doesn't include elements such as learning, studying, or observing as 训练 does
You can 训练 yourself in chess, but you cannot 操练 your chess skill because it is not a set routine.
We usually say 操练 martial art set (e.g. perform a Tai Chi set) because it is a set routine. The more you repeat, the better you get at it