Difference between handling and grip?

[haynes]

Opinions seem to be that 5 to 5.5" wide 10s with minmal offset are the best handling. But wider track / tyres etc offer more grip. Just curious what the difference between grip and handling is. Is it that, like in the early days of mini competiton an underpowered car could out handle a bigger heavier machine by sliding sideways through the corners but now a 140hp miglia has the power to use 7" wide slicks and loads of grip?