The difference between the words "Loose" and "Lose" is in both the length of the vowel, and the sound made by S. In "loose", S is voiceless, while "lose" makes S sound like Z.
Listen along and improve your own ability to lengthen your vowel sounds, and change S to Z sounds.
If you're looking for more material on this topic, check the links below to keep things moving forward!
Check out my video course on Udemy to kick-start your AccenTraining Journey!
Stretching Vowel Sounds
S as Z Word Endings
Es as Iz Word Endings
S as Z midword