What are the changes that search engine optimization goes more specific, these past 2 Years?

Mobile (google mobile friendly and AMP for details), and content/social media. These are two biggest changes that search engines like Google been adapting to. Websites owners and experts should look in to: how to deliver their content into these devices just like big search engines are doing right now.

Question is not clear. As far I understand you want to know what search engines are changes since 2 years. Google itself do 500-600 changes every year. It includes all minor major changes. Recently Google and other search engines are doing mobile specific changes. Below are some details

1- Mobile First Index

2- AMP implementation

3- Mobile Friendliness is compulsary

4- No Pop ups on Mobile version of websites

5- Deep Link for your Apps

There are many other changes like Fred update to counter low quality content and some other updates on low quality links.

First, there’s the rise of content marketing as part of a successful SEO strategy. Google has steadily refined what it considers to be “good” content over the years, but it was the Panda update in 2011 that served as the death blow to spammy content and keyword stuffing.

After Panda, it was virtually impossible to get away with any gimmicky content-based tactics, such as favoring a high quantity of content while forgoing quality and substance. Instead, the search engine winners were ones who produced the best, most valuable content, spawning the adoption of content marketing among SEOs — and content is still king today.

1. Personal blogs used primarily for building links TO your site will gradually die.
2. Anchor text will still matter but excessive use of keywords in anchor text will be penalised.
3. Site loading speed will matter.
4. Now, as desktop and mobile search have separated, mobile responsiveness will be a must, ideally use of AMP (Accelerated Mobile Pages) is advised.
5. Social media (mentions) will be taken into account.
6. Use of Structured Data (Schema) will be appreciated.
7. Link quality will be a factor.
8. Quality of content will be take into account.
9. Technical aspects, architecture and design will also be a factor but not a major one. And last but not the least
10. User experience will also matter.

The last5 factors are the ones that have been voted for by SEO experts.

Social Media has become one of the evaluating  factors, I've been to one of the Google Seminars in London, And they have mentioned that the next SEO will be based on mentions on Social media .

This is a big turn of the event. 

Improvement in the algorithms used to include current in technology requirements. I agree with Mr. Ahmed Khair

I am sorry, I did understand the question

1- Mobile First Index

2- AMP implementation

3- Mobile Friendliness is compulsary

4- No Pop ups on Mobile version of websites

5- Deep Link for your Apps

They have included Social media in their algorithms 

In the past two years, Penguin algorithm finally updated again fourth time making it Penguin 4.0. As we know that Penguin filter was introduced in 2012 but it has controlled on a periodic basis. The last Penguin update was in October 2014. The Penguin filter would run and captivate websites viewed as spammy. Those sites would remain penalized even if they improved and changed until the next time the filter run, which could take months. However, this new Penguin 4.0 filter will run on constantly basis, so the web pages will be caught and/or relieved by Penguin as part of this regular process.

Google also informed that there will be no announcement regarding Penguin update in the future as the recent update will be working constantly. 

Other changes in SEO like Hummingbird and Mobilegeddon update. 

I'm not sure what you by "goes more specific" but the major changes that Google had in the past 2 years when it comes to organically rank websites are historically:

1. Onsite content and the structure of the website. That include all site's meta tags, alt tags, content, anchor text..etc.

2. Responsiveness and how mobile friendly is the website.

3. The most recent update or change is Live Actions. If a website spotted doing link farming or hidden keywords or any form of black hat optimization, it is immediately banned. Once the problem is solved, the website will also immediately be removed from the banned list.

Hope that makes sense you and answers your question.