Although, they might sound very similar and some aspects are shared there are a few recognisable differences between these two different social media features.
With access to your company Facebook page you can; publish updates, post images, videos, share other content and so on. Those people / businesses who have liked your page can then see this published content. More than likely your updates will appear in their news feeds. Therefore, those people that are already connected with your Facebook page primarily see this content. In some instances, for example, one of your followers likes an update of yours then their friends might see it in their news feeds that they have liked your Facebook page. However, unless you are linking to your Facebook page from a website, spending the time to find new followers or encouraging people in store to like your business page, then your Facebook following is likely to be very small.
Facebook advertising is in a way a different type of content that is being published on your Facebook page, it is a paid form of advertising in which you allocate a budget to Facebook, create an advert, choose your audience and publish your ad. Now the benefits of Facebook advertising is that it allows you to specifically target your ads to a group of people that you think are likely to be interested in your business or the goods/services that you have on offer.
Similarly to normal Facebook updates, Facebook Ads allows you to create ads in a variety of formats. By this, I mean you can have an image ad, a text ad, a video ad, an ad that directs to a product on your web page and so on. You simply assign a budget that you are happy to spend, choose the dates in which you want your ad to run from and when you would like the ad to end. You can then choose the audience that you would like your ad to be shown to. You can target by age, location, gender, interests, job description and much more.
Therefore, the main difference between normal post updates on Facebook and advertised posts is the ad reach. Facebook ads can be displayed to a lot more people and due to the advertising targeting options the ad is often shown to a lot of relevant people.
If you are looking to increase your brand awareness, publicise an offer or even provide people with some informative important content, then Facebook advertising is definitely worth considering.