Essentially, as a Lexus owner, you're being offered an extra layer of cover if you remain faithful to the dealer network and you get it serviced within in the recommended intervals. There are no complex clauses, exclusions or caveats as it's supposed to be easy for owners to understand and benefit from. The idea is to simplify servicing and warranties for customers. However, I would suggest you read the terms and conditions of the extended warranty because there are some exclusions to be aware of: d3rvezpmgp265q.cloudfront.net/lexusone/lexgbenv11/...f

In short, from what I've seen in the Ts&Cs (which I've linked you to above), there are some major exclusions under the Relax scheme which may be covered by your extended warranty. These include but aren't limited to maintenance parts, rubber parts, body and paint, multimedia systems etc. This means components that are excluded from cover include brake pads, wheels and tyres, belts and tensioners, batteries (in non-hybrid models), spark plugs, rubber parts, shock absorbers, infotainment systems, paintwork, lights, seat covers, 12v socket, exhaust system (including cat. converter) etc.

So, the point of the Relax scheme is to keep/bring back owners into the Toyota/Lexus servicing network. This is good in many ways because Lexus itself will offer the best Lexus servicing with genuine parts (though, it'll be more expensive than using an independent garage). I believe the Relax warranty itself is free, too, as it's automatically applied at each service. The best way to determine the difference between the warranties would be to look at the Ts&Cs of both. If you give your local Lexus dealer a ring, they'll probably be able to offer some clarity, too. You can then make a decision once you're armed with the facts of both warranties.