On dedicated, the address is yours alone for the period. On shared, it stays with three customers at most at the same time. Both have no bandwidth cap, HTTP on port 20001, SOCKS5 on 20481 and UDP.
The price
Five dedicated cost US$ 6.25 a month. Ten shared cost US$ 6.25 a month. From there the package grows, and the price per address drops on the larger packages. The full table is on the pricing page.
Choose dedicated when the reputation of the address matters and you do not want to share it. Choose shared when what matters is quantity for the same money.