Both of the racquets you referenced are made of lower quality materials. They're not necessarily "bad" racquets (especially for a beginner such as yourself) but they differ from higher quality racquets in specific ways such as:
- They can't be restrung if needed (they will bend/warp during the re-stringing process)
- They generally are much lighter weight than higher quality racquets made of graphite and so they will produce more vibration each time you hit the ball.
Higher quality racquets are generally going to cost somewhere between $150 and $200 when purchased new from a shop. If possible, I would recommend buying from an actual tennis shop - the big chain stores like Sports Authority, Sports Chalet, Big 5, etc. generally don't have very knowledgeable employees when it comes to tennis equipment. Most tennis shops also have a demo program where they let you take racquets you're interested in and go try them out before you buy anything. Most of the big chain stores do not have demo programs.
The racquets you referenced were probably around $30 (I'm guessing) so the jump to paying $150 or more for a racquet might seem like a big investment. This is another reason to try and find a tennis shop - they might have some used (demo) racquets they want to sell and you could get a really good deal (like half-price) on a higher quality racquet that would still last you a long time.
Also - since you're a beginner, look for a racquet that has at least a 100" sq. in. head size. This will give you a bigger area to hit the ball with, a bigger sweet spot, and more stability on contact. It will also give you easier power.