England, who got off to a winning start against Argentina on Wednesday, rotate their options in the squad, with Heyes and Lewis coming into the starting pack after a role from the bench in midweek.
England face Italy in Perpignan, with kick-off at 3.30pm UK time on Sunday. The game will be streamed live on WorldRugby.org with highlights on ITV 4 at 11.00pm.
Head coach Steve Bates makes nine changes to the starting XV with the side captained by Sale Sharks flanker Ben Curry.
Northampton prop Toby Trinder has been ruled out of the tournament with an injury picked up in Wednesday’s opening fixture so James Kenny (Exeter Chiefs) has been called into the squad as a replacement.
Bates said: “Getting off to a winning start in this tournament is really important as it gives you momentum and confidence early on. What we’re looking for against Italy is an improved performance across the board. We need to be more accurate, be patient and to play for longer as well as try and turn more of the opportunities we created against Argentina into scores.
“There are some different combinations, the side we’ve picked is really exciting with threats all over the pitch and I’m really looking forward to seeing them play.”
Tigers flanker Tommy Reffell retains his place as captain of Wales Under-20s who make just one change to their team for the pool match against New Zealand in Béziers (3.30pm UK time).
The change is enforced, with wing Rio Dyer ruled out of the tournament due to a shoulder injury. His place goes to Dragons team-mate Joe Goodchild.
"We were delighted to come away with a good win that was full of positives against Australia," said head coach Geraint Lewis. "But we know New Zealand will be another step up for us. Thankfully we've got the desire and hunger to improve within this squad.
“The players are excited about pitching themselves against the best in the world at this level, and there's been a real buzz around the camp for tomorrow's game."
Sam Grahamslaw is given his first start of the Championship for Scotland as they face Argentina with both sides searching for a first win.
The Tigers prop was used as a second-half replacement in Wednesday’s one-point defeat by Italy but is elevated to the XV as part of six changes made by head coach Bryan Redpath for the game in Perpignan (1.00pm UK time).
Former Tigers academy wing Sam Yawayawa, now with Glasgow Hawks, is also named in the team.
On his team selection, Redpath, said: “We were obviously disappointed with how the match against Italy ended. I thought we were outstanding for 90 per cent of the match, but there were three instances where we didn’t manage to get it right in the final five minutes and we learned that you pay a heavy price for things like that at this level.
“We’ve made a few changes to the starting XV to keep things fresh and we’re expecting a tough match from a well-drilled and physical Argentinian side.”
England U20s: 15 Tom Parton (London Irish), 14 Gabriel Ibitoye (Harlequins), 13 Fraser Dingwall (Northampton Saints), 12 Will Butler (Worcester Warriors), 11 Ben Loader (London Irish), 10 Marcus Smith (Harlequins), 9 Rory Brand (London Irish); 1 Alex Seville (Gloucester Rugby), 2 Henry Walker (Gloucester Rugby), 3 Joe Heyes (Leicester Rugby), 4 Joel Kpoku (Saracens), 5 Sam Lewis (Leicester Tigers), 6 Tom Willis (Wasps Rugby), 7 Ben Curry (Sale Sharks)(c), 8. Josh Basham (London Irish)
Replacements: 16 Gabriel Oghre (Wasps Rugby), 17Ciaran Knight (Gloucester Rugby), 18 Ehren Painter (Northampton Saints), 19 James Scott (Worcester Warriors), 20 Aaron Hinkley (Gloucester Rugby), 21 Ben White (Leicester Tigers), 22 Tom Hardwick (Leicester Tigers), 23 Jordan Olowofela (Leicester Tigers)
Scotland U20s: 15 Paddy Dewhirst (Ayr), 14 Logan Trotter (Stirling County), 13 Cameron Hutchison (Currie Chieftains), 12 Stafford McDowall (c)(Ayr), 11 Sam Yawayawa (Glasgow Hawks), 10 Callum McLelland (Edinburgh Rugby), 9 Charlie Chapman (Gloucester); 1 Sam Grahamslaw (Leicester Tigers), 2 Finlay Scott (Jed-Forest), 3 Murphy Walker (Strathallan School), 4 Jamie Hodgson (Watsonians), 5 Marshall Sykes (St Joseph's College), 6 Guy Graham (Newcastle Falcons), 7 Rory Darge (Melrose), 8 Devante Onojaife (Northampton Saints)
Replacements: 16 Robbie Smith (Ayr), 17 Ross Dunbar (Boroughmuir), 18 Finlay Richardson (Edinburgh Accies), 19 Charlie Jupp (Heriot’s), 20 Martin Hughes (Heriot’s), 21 Charlie Gowling (Stade Francais), 22 Ross Thompson (Glasgow Hawks), 23 Fraser Strachan (Northampton Saints)
Wales U20s: 15 Cai Evans (Ospreys), 14 Joe Goodchild (Dragons), 13 Corey Baldwin (Scarlets), 12 Ioan Nicholas (Scarlets), 11 Ryan Conbeer (Scarlets), 10 Ben Jones (Cardiff Blues), 9 Dane Blacker (Cardiff Blues); 1 Rhys Carre (Cardiff Blues), 2 Iestyn Harries (Cardiff Blues), 3 Rhys Henry (Ospreys), 4 Rhys Davies (Bath Rugby), 5 Max Williams (Dragons), 6 Tommy Reffell (c) (Leicester Tigers), 7 Dan Davis (Scarlets), 8 Taine Basham (Dragons)
Replacements: 16 Dewi Lake (Ospreys), 17 Rhys Davies (Scarlets), 18 Will Davies-King (Cardiff Blues), 19 Lewis Ellis-Jones (Scarlets), 20 Lennon Greggains (Dragons), 21 Harri Morgan (Ospreys), 22 Ben Thomas (Cardiff Blues), 23 Dewi Cross (Ospreys)