Differernce beteween Top-Down Parser and Bottom-up Parser

Top Down Parser

• expansion of parse tree
• backtracking
• use recursive descent parsing
• follow LL parser
• use leftmost derivation (token consumed from left to right)

Bottom-up Parser

• reduction of a parse tree
• no backtracking
• use shift-reduce parsing
• follow LR parser
• use rightmost derivation(token consumed from right to left)