IIRC, it can be one or the other, but not both, since the spell point progression in the DMG variant rules is slower than spell slot progression in the PHB.
Up until level ten, they're exactly identical.
PSI = Spellpoints = Spellcaster slot progression
(Not counting class features such as sorcery points etc, obvs)
4 points is equal to 2+2; 2 L1 slots
6 points is equal to 2+2+2; 3 L1 slots
14 points is equal to 3+3+2+2+2+2; 2 L2 slots + 4 L1 slots
17 points is equal to 3+3+3+2+2+2+2; 3 L2 slots + 4 L1 slots
27 points is equal to 5+5+3+3+3+2+2+2+2; 2 L3 slots + 3 L2 slots + 4 L1 slots
32 points is equal to 5+5+5+3+3+3+2+2+2+2; 3 L3 slots + 3 L2 slots + 4 L1 slots
38 points is equal to 6+5+5+5+3+3+3+2+2+2+2; 1 L4 slot + 3 L3 slots + 3 L2 slots + 4 L1 slots
44 points is equal to 6+6+5+5+5+3+3+3+2+2+2+2; 2 L4 slots + 3 L3 slots + 3 L2 slots + 4 L1 slots
57 points is equal to 7+6+6+6+5+5+5+3+3+3+2+2+2+2; 1 L5 slot + 3 L4 slots + 3 L3 slots + 3 L2 slots + 4 L1 slots
64 points is equal to 7+7+6+6+6+5+5+5+3+3+3+2+2+2+2; 2 L5 slot + 3 L4 slots + 3 L3 slots + 3 L2 slots + 4 L1 slots