P and B use the same lips; the difference is voice and a puff of air. Arabic has no /p/, so speakers often say b for both, and park sounds like bark.
Hold a hand in front of your mouth. A strong English P at the start of a word gives a puff of air you can feel; B gives almost none.
20% of 12,623 scored /p/ sounds in the SayWhat app were scored red, from at least 4,967 learners.