Q: Upgrade Macbook late 2009 RAM Only

I would recommend updating to 8 GB of RAM (the Max for your model). Upgrading the RAM will make a difference if you're using more than one or two apps at a time. If you're just surfing the web and doing email, the differences will be just noticeable.

The SSD upgrade would be a very noticeable improvement, as the stock 5400 rpm HDs are dog slow.

Recommend OWC as source for both upgrades.

https://www.macsales.com

Adding Ram will have only a minor effect on performance, it will reduce disk swapping, if that is happening. Using an SSD will provide a significant boost to performance (much more than Ram) under all circumstances.