lsof -p PID vs lsof | grep PID

I do not understand the output of the lsof command. When I write: lsof -p PID I get 4 lines, and when I write: lsof | grep PID I get hundreds of lines. Shouldn't it return the same result? Here are some sample outputs. Looks like it is a subprocess, or what do those tasks mean? lsof -p 29076 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME java 29076 pr cwd unknown /proc/29076/cwd (readlink: Permission denied) java 29076 pr rtd unknown /proc/29076/root (readlink: Permission denied) java 29076 pr txt unknown /proc/29076/exe (readlink: Permission denied) java 29076 pr NOFD /proc/29076/fd (opendir: Permission denied) lsof |grep 29076|head -20 java 29076 pr cwd unknown /proc/29076/cwd (readlink: Permission denied) java 29076 pr rtd unknown /proc/29076/root (readlink: Permission denied) java 29076 pr txt unknown /proc/29076/exe (readlink: Permission denied) java 29076 pr NOFD /proc/29076/fd (opendir: Permission denied) java 29076 300 pr cwd unknown /proc/29076/task/300/cwd (readlink: Permission denied) java 29076 300 pr rtd unknown /proc/29076/task/300/root (readlink: Permission denied) java 29076 300 pr txt unknown /proc/29076/task/300/exe (readlink: Permission denied) java 29076 300 pr NOFD /proc/29076/task/300/fd (opendir: Permission denied) java 29076 329 pr cwd unknown /proc/29076/task/329/cwd (readlink: Permission denied) java 29076 329 pr rtd unknown /proc/29076/task/329/root (readlink: Permission denied) java 29076 329 pr txt unknown /proc/29076/task/329/exe (readlink: Permission denied) java 29076 329 pr NOFD /proc/29076/task/329/fd (opendir: Permission denied) java 29076 330 pr cwd unknown /proc/29076/task/330/cwd (readlink: Permission denied) java 29076 330 pr rtd unknown /proc/29076/task/330/root (readlink: Permission denied) java 29076 330 pr txt unknown /proc/29076/task/330/exe (readlink: Permission denied) java 29076 330 pr NOFD /proc/29076/task/330/fd (opendir: Permission denied) java 29076 331 pr cwd unknown /proc/29076/task/331/cwd (readlink: Permission denied) java 29076 331 pr rtd unknown /proc/29076/task/331/root (readlink: Permission denied) java 29076 331 pr txt unknown /proc/29076/task/331/exe (readlink: Permission denied) java 29076 331 pr NOFD /proc/29076/task/331/fd (opendir: Permission denied)