Are these two statements the same performance wise?
According to the official MySQL Documentation (How MySQL Optimizes WHERE Clauses) MySQL will optimize the WHERE clause as follows:

Each table index is queried, and the best index is used unless the optimizer believes that it is more efficient to use a table scan. At one time, a scan was used based on whether the best index spanned more than 30% of the table, but a fixed percentage no longer determines the choice between using an index or a scan. The optimizer now is more complex and bases its estimate on additional factors such as table size, number of rows, and I/O block size. 

(Please read the full documentation)

There is a small disclaimer at the top of the article which states: 

Note:  
Because work on the MySQL optimizer is ongoing, not all of the optimizations that MySQL performs are documented here. 

Based on the quoted article MySQL should run both statements using the same execution plan and the supplied index.