Oil paints are long-lasting, but discolor with age. Acrylic paints seem not to discolor, but have not been used for as long as oil paints, so it is not possible to be completely sure about this assumption. Oil paints contain a lot of pigment and their colors are dramatic and vibrant. This paint does not darken during the drying period, as acrylic does. Acrylic paints are also not as bright as oils.
The most significant difference between oils and acrylics is the time each takes to dry. Oil paints take a several days to dry and will stay wet for a number of weeks if the temperature and humidity is not correct. Acrylics, however, dry within an hour, making it difficult to mix acrylic paints on canvas. If you use oil paints, you can blend colors on canvas for days, to create very subtle color tones. With acrylic paint, you are able to allow a spot to dry and quickly correct a mistake by painting over it, something not possible with oil paints. If you work in a very deliberate fashion, you might be more comfortable using the slow drying oils.
Acrylic paint is more versatile than oil paint, which makes it very suitable for novice artists who want to experiment with different painting styles. It is possible to dilute acrylics and use them as you would watercolors, which is definitely not possible with oil paints. On the other hand, it is possible to apply acrylic paint thickly to create the same impasto effect artists traditionally used oil-based paints for. You can also add a “retarder” to acrylic paint, which will make it thicker and slow the drying time.
You will have to clean your brushes straight after using acrylic paints to prevent the bristles from becoming caked with dried paint. This will not happen with oil paints, but you will need mineral spirits or turpentine to clean brushes used with oil paints. You can clean up with water after using acrylic paint, which is much more convenient. Oil paints are more expensive than acrylic paints; making the latter more suitable cost wise if you are not sure of your preferred painting-style yet.