Professional is sometimes used to describe a persons countenance or manner in that they act professionally in whatever they do. Professional sometimes means a learned skill and that is where professional SEO would comfortably sit. Make no mistake any SEO is a skill and its not a skill that is easily learned or taught. You could find all manner of tutorials and advice online about doing your own SEO but that will in no way cover the amount of knowledge you ultimately need to provide excellent search engine optimized websites. There are some aspects of SEO that you could do yourself and do well, but for the best results you probably do need professional SEO help.
Finding a good SEO company can be tricky as they will all make bold claims but only some of them will be genuine. As to the difference between good and bad SEO its a huge gap with very bad SEO sometimes resulting in your website being banned and dropped from search engines. Good SEO will almost certainly result in you gaining a bigger foothold in your particular field with an increase in customers or sales. Ultimately you need to be able to place your trust in whoever you choose for your SEO work and to be able to do that there has to be a good and easy level of communication.
Any SEO company that talks in SEO terms without explaining what they are to you so you gain understanding is not going to be a good or professional SEO company. SEO isnt a heavily regulated field so the potential for bad practice is high and for every good, ethical and trustworthy company youre likely to find 10 the exact opposite. Anyone can call themselves a professional SEO company and unlike a lot of professions there is no standard training, qualifications or even guidance. SEO is skill and a highly skilled person in that field will definitely be someone you want to do work on your behalf. You can learn SEO techniques and methods but what counts most is experience.
Experience can make the world of difference in your website optimization experience will tell a person what will and wont work for you. Experience will tell anyone working on your SEO that your business doesnt necessarily need the same as another business working in the same field. Each company is unique in their set up and the way they work and a website which works for one may not work for another. Your uniqueness needs to be taken into consideration when planning your website so that the end result completely matches your needs and the way you do things. A Professional SEO will be an experienced SEO.
The ultimate goal of any search engine optimization on a new website or an already established website is to generate more business and get you higher up the results of online searches. Unfortunately you cant know that the SEO work you have had done and paid for will produce any results and that is why you need to choose your Professional SEO company with care. Fly by night scammers can be very convincing and will take your money and leave you with a website that isnt generating any new business because it hasnt been fully optimized. Use only SEO companies that are well established with published results and successes and you should be fine and get that extra custom you need.