think you !
in my opinion:
NO.1 JPG is the 8051 P1
NO.2 JPG is different ,it is PIC PORTC output .it has tow CMOST Q1 and Q2.because Q1 and Q2 is CMOST, so we could equate it is two "switch" like as NO.3 JPG . when PORTC output 1, Q1(S1) close ,power(vdd) will direct add to LED.
so LED will be very brightness. but LED's "P-N" will fixup the voltage at 0.7V, and the residual voltage(5V-0.7V=4.3V) will be expend by PIC ,so PIC will soon be very hot .
so i suggest that we could add a resistance seriated as NO.4 JPG
are you agree?