Opener Roy and wicketkeeper-batsman Bairstow, who are currently ranked 11th and 14th, respectively, in the ICC Men's ODI Player Rankings, could work their way back into the top 10, having both enjoyed personal best rankings of ninth position in the past. Roy was in ninth place in July last year and Bairstow in October 2018.
World Cup-winning captain Eoin Morgan, who is the third best-ranked batsman from his side in 23rd position, will be leading against a side for whom he scored 99 on ODI debut against Scotland 14 years ago.
With none of the England players featuring in the Test series against the West Indies named for the ODIs, England will be missing their premier fast bowlers and will be led by spin twins Adil Rashid (29th) and vice-captain Moeen Ali (44th).
For Ireland, skipper Andy Balbirnie, who took over from long-time skipper William Porterfield last November and has only led in a three-ODI series in the Caribbean in January, is ranked 46th among batsmen.
Paul Stirling remains their top-ranked batsman in 27th position, having held a career-high position of seventh in 2013.
Off-spinner Andy McBrine (31st) and paceman Boyd Rankin (joint-40th) are their leading bowlers according to the rankings.
The series marks the start of the much-awaited Super League that will see 13 teams vie for direct qualifying places in the next World Cup in India in 2023.
India and seven other teams will make it directly from the league with the remaining two getting a second chance at qualifying through a Qualifer. Teams will be awarded 10 points for a win, five for a tie, no-result or abandoned match and none for a loss.