Nick McCarthy returns at scrum half with Ryan Foley dropping back to the bench, while Peadar Timmins and Frankie Taggart are restored to the back row with Josh Murphy and Rory Moloney making way.
Speaking ahead of the much-anticipated game, Ruddock said: "England, the current World champions, are our next opponents and it doesn't get any bigger than that. They will be confident after beating us in the Six Nations, but we have improved since then. Nothing less than our 'A game' will do."
Meanwhile, the Irish squad took time out from their match preparations to participate in the Junior World Championship legacy programme, with a visit to the local Three Kings Primary School.
Sunday's semi-final showdown will be broadcast live on TG4 (kick-off 5.05pm local time/6.05am Irish time), with coverage also available on Sky Sports 2 HD and the www.irb.com live stream.
To listen to a preview interview with Ireland captain Jack O'Donoghue, click here.
IRELAND UNDER-20 Team & Replacements (v England Under-20s, 2014 IRB Junior World Championship - Semi-Final, QBE Stadium, Auckland, New Zealand, Sunday, June 15, kick-off 5.05pm local time/6.05am Irish time):
15. Cian Kelleher (Lansdowne/Leinster)
14. Ciaran Gaffney (Galwegians/Connacht)
13. Garry Ringrose (UCD/Leinster)
12. Dan Goggin (Young Munster/Munster)
11. Alex Wootton (Garryowen/Munster)
10. Ross Byrne (UCD/Leinster)
9. Nick McCarthy (UCD/Leinster)
1. Peter Dooley (Lansdowne/Leinster)
2. Max Abbott (Cork Constitution/Munster)
4. Stephen Gardiner (Lansdowne/Leinster)
5. Ross Molony (UCD/Leinster)
6. Peadar Timmins (UCD/Leinster)
7. Frankie Taggart (Belfast Harlequins/Ulster)
8. Jack O'Donoghue (UL Bohemians/Munster) (capt)
16. Dylan Donnellan (UCD/Leinster)
17. Denis Coulson (Lansdowne/Leinster)
18. Oisin Heffernan (Lansdowne/Leinster)
19. Darragh Moloney (Cork Constitution/Munster)
20. Rory Moloney (Buccaneers/Connacht)
21. Ryan Foley (Cork Constitution/Munster)
22. Conor McKeon (Lansdowne/Leinster)
23. Harrison Brewer (Terenure College/Leinster)
IRELAND - POOL B RESULTS:
Monday, June 2: France 19 IRELAND 13, QBE Stadium, Auckland
Friday, June 6: Wales 21 IRELAND 35, ECOLight Stadium, Pukekohe
Tuesday, June 10: IRELAND 38 Fiji 0, QBE Stadium, Auckland
For the full fixtures list, please click here.