The ATPL exams are SIGNIFICANTLY greater than the IR exams. Don't listen to all the waffle and bull**** on this site about how long and time consuming the IR exams are when what they are referring to is being hoodwinked into selling their sole to do the 14 ATPL exams and all the stuff that goes with it.
The usual line is you might want to go commercial in the future so do the whole lot now. Well unless you want to sit in a people tube you dont need an ATPL. Unless you get multi crew jet time you won't get the ATPL 'unfrozen' and the exams expire after 5 years. If you do the ATPL exams and only do the IR the exams for the CPL side expire in 18 months.
If you do the IR and want do the CPL later then you do the CPL exams when you are ready.
The IR exams are not hard.