<p>The difference between them are:</p>
<p>Previous Company 401K, Cannot borrow from it, Limited investment options to choose from.
Brokerage IRA, Cannot borrow from it, Can invest only in general investment instruments, stocks, bonds, options, mutual funds.
Current Company 401K, May not borrow from rollover, even if you can borrow, interest rates are set by the company, Limited investment options.
Solo 401K, Can borrow from it and you set the interest rate, flexible investment options including real estate.</p>