Using your example: TILGX the expense ratio is 0.41%.
Use a popular SP500 ETF IVV, the expense ratio is 0.03%
The difference is 0.38% you pay more for TILGX than IVV. Of course I don't know if TILGX outperforms IVV over long term.
And I don't know if there are other management fees in your TIAA 401K. Usually 401K is a money maker for the brokerage than IRA.