Leverage trading

What is the difference between obtaining leverage through pledging of holdings and the leverage in margin trading in equity intraday? I mean if we do intraday in equity cash segment we can get leverage by pledging our holdings and also by maintaining the required margin, so what is the difference between them? And what exactly happens if my losses go beyond the required margin and my fund shows a huge negative balance in case of volatility and my broker was unable to square off the position? In this case when will my position get square off? Will it get square off after market closes? And what consequences will i have to face? And what consequences do my broker face?