Stanford's Civana Kuhlmann and USC's Savannah DeMelo also scored against Sweden, which fielded a U-23 team.
Against England's U-20s, Smith struck in the 36th minute.
Coach Jitka Klimkova's U.S. team, which is preparing for the 2018 U-20 World Cup in France (Aug. 5-24), faces Italy on Monday.
April 7 in La Manga,
Spain
USA U-20 1 England U-20 0.
Goal: Smith 36.
April 5 in La Manga, Spain
USA U-20 4 Sweden U-23 1.
Goals: Smith 25, Kuhlmann (Pickett) 45, Smith 46, DeMelo (Kim) 64; Andersson
69.
USA
-- McGlynn, Pickett, Morse, Rodriguez, McKeown (Brewster, 68), Howell, DeMelo (Coffey, 68), Pinto (Villacorta, 46), Kuhlman (Kim, 46), 3 Smith (Hocking, 68), Turnbow (Sanchez, 46).
Sweden -- Haglund, Aronsson, Pennsater (Rybrink, 46), Okvist, Stahl (De Jongh, 58), Angeldal, Blomqvist (Jansson, 73), Anvegard, Almqvist, Andersson, Curmark (Wieder, 58).
U.S. U-20 women's national team
GOALKEEPERS (3): Brooke Heinsohn (Duke; Norfolk, Mass), Laurel Ivory (Virginia; Surfside,
Fla.), Amanda McGlynn (Virginia Tech; Jacksonville, Fla.).
DEFENDERS (8): Jordan Brewster (Internationals SC; North Canton, Ohio), Naomi Girma (California Thorns FC; San Jose,
Calif.), Samantha Hiatt (Stanford; Newcastle, Wash.), Tara McKeown (USC; Newbury Park, Calif.), Zoe Morse (Virginia; East Lansing, Mich.), Kiara Pickett (Stanford; Santa Barbara, Calif.), Isabel
Rodriguez (Ohio State; Canton, Mich.), Karina Rodriguez (UCLA; Torrance, Calif.).
MIDFIELDERS (6): Samantha Coffey (Boston College; Sleepy Hollow, N.Y.), Savannah DeMelo (USC;
Bellflower, Calif.), Jaelin Howell (Real Colorado; Windsor, Colo.), Taylor Kornieck (Colorado; Henderson, Nev.), Brianna Pinto (NTH Tophat; Durham, NC), Viviana Villacorta (UCLA; Lawndale, Calif.).
FORWARDS (7): Penelope Hocking (So Cal Blues; Anaheim, Calif.), Abigail Kim (California; Vashon, Wash.), Civana Kuhlmann (Stanford; Littleton, Colo.), Ashley Sanchez (UCLA;
Monrovia, Calif.), Sophia Smith (Real Colorado; Windsor, Colo.), Taryn Torres (Virginia; Frisco, Texas), Kelsey Turnbow (Santa Clara; Scottsdale, Ariz.).