There is a huge performance difference. Assuming both CPUs are clocked at the same speed, the dual core mobile Core i5 will have around 25% more processing power than the Turion.
the core i5 supports most of the latest tech. has quick sync, turbo boost 2.0, aes-ni, vt-d. it is more power-performance efficient than previous gen cpus. it is much faster than the turion.