The difference between the two types of DDR3 is in their supported voltages. Normal DDR3 requires 1,5 Volt, whereas DDR3L (L for Load reduced) also supports 1,35 Volt. This reduction in voltage results in a slightly lower power consumption. However, this reduction is so small, that the difference in battery life caused by using load reduced RAM even in laptops is hardly noticeable. It only makes a difference in data centers with hundreds of computers, each with up to 32 memory modules.
Even though the power consumption difference is tiny, you have to watch out for compatibility. Systems, which only support normal DDR3 usually, work with DDR3L, too, because it also supports 1,5 Volt. But there are computers, especially laptops, which only support DDR3L. Normal DDR3 might work here, however this is not guaranteed and might come with some stability issues. So, if you are not sure, which type of DDR3 your system needs, it is better to buy the load reduced variant or consult an expert.