firstly whats the difference b/w a counter and timer

i know that a counter+osciallaor makes a timer but whats the difference theorically speaking


Now I undertsand how to use the TCOn and TMOD like if I want to write a program to blink a LED after each second, 1 second delay then :-
I select timer 0 , timer mode 16 bit….

Now I have to play with timer TH0 and TL0 functions….
But I don’t understand the calculation work that I have to do before writing the code…

Like iam using 12 Mhz crsytal
That means

Timer will increment 1000000 times per second.

Now I have to divide 1000000 by such number that shows that the 1 second has passed

1000000 / 1000000 = 1 second has passed

So the timer has to count from 0 to 1000000

But in case of 16 bit timer will count maximum value of 0 to (256 x 256 = 65536 times )

Lets take a round of value like 50000 .

Now I know the following instruction helping me in writing a code for 1 second or 1 minute but how to make calculation to get values for the following equation to get a delay of 1 second or 1 minute

MOV TH0,___;High byte of _______ (____ * 256 = ?)
MOV TL0,#01;Low byte of 1 (? + 1 = ?)
MOV TMOD,#01;Put Timer 0 in 16-bit mode
SETB TR0;Make Timer 0 start counting
JNB TF0,$;If TF0 is not set, jump back to this same instruction