Is this true or false and Explain.

There is a time lag between E-mini S&P 500 futures and the major stock
in S&P 500 index (such as IBM, MSFT, GE)? For example, Futures price
moves up, then few seconds the major stock will follow the futures
price direction.

If ture, why is there time lag?

You need to understand what the futures market is about first. Go to
www.cme.com   It is not directly tied to anything.  It is simply a bet
on which direction the S&P 500 will go.  Because the S&P 500 is the
'fair value' of the e-mini, these two will track closely to one
another, BUT NOT ALWAYS.

If you are planning on trading the e-mini. Study and practice a lot,
else you will lose your shirt.