Assuming you mean the Edwardian terrace houses (Caxton, Tennyson, Dryden, Milton, Cowper, Dryden) rather than the newer 90's built estate closer to Colliers Wood and on the opposite side of Wandle Meadow Nature Reserve then no difference at all really.
Haydons Road is a 'mind barrier' for people so houses on the Wimbledon side cost £100k+ more than the poets side, it has the same postcode, same constituency, same school catchment and is (currently) in the same Council Ward. I can only assume it's just the 'feeling' it is just that extra few steps too far for some to Wimbledon but it's a less than a 20 min walk to the mainline station, it's next to Haydons Road (Thameslink) and Northern Line is about 10-15 min walk away. Don't let the price concern you. The area North of the rail line is not technically part of 'Poets' but is the same housing stock and I'd say pretty much the same thing about it. Only advice I'd give is go for houses that are furthest away from Haydons/Plough Lane to avoid traffic noise, it's up to you how close to the rail line you can stand but they don't run late and currently only run once every 30 minutes.