Complex sentence: The first batch was built at Hillside Workshops in 1946--56 and the second batch by the North British Locomotive Works in 1951, and to distinguish between the batches, locomotives are identified by their maker.
Split into simpler sentences: The first batch was built at Hillside Workshops in 1946--56 and the second batch by the North British Locomotive Works in 1951. To distinguish between the batches, locomotives are identified by their maker.