perder vs faltar
Perder is losing something. Faltar is something being missing or absent — the gap itself.
perder
To lose — an active experience where something slips from your possession or control.
He perdido el pasaporte.
I've lost my passport.
You had it and now you don't. The losing is something that happened to you.
Perdieron el partido.
They lost the match.
To lose a game or competition. Always perder.
No pierdas el tiempo.
Don't waste your time.
Perder el tiempo = to waste time. Fixed idiom.
faltar
To be missing, to lack, to be absent — it works like gustar (the missing thing is the subject).
Me faltan cinco euros.
I'm five euros short.
The euros are what's missing — they're the subject. Me = indirect object. Like gustar.
Falta María.
María is missing / María hasn't shown up.
María is absent. Nothing was lost — she just isn't there.
Falta poco para llegar.
We're nearly there. / Not far now.
Time or distance remaining. Very common in travel contexts.
Tricky bit
'Me falta práctica' = I lack practice (it's missing from my life). 'Perdí la práctica' = I lost the skill I once had. One is about absence, one is about losing something you possessed. Different feelings entirely.