Looking back over the decades...
My incoming graduate class had both fresh university graduates and those who had worked (mainly in engineering positions at, say, IBM or GE) for a while (including more than 9 years). Broadly speaking, those who had worked for a while struggled more with coursework because they were out of practice with the whole lectures/problem sets/exam routine. On the other hand, they knew why they were going to grad school better than the fresh graduates - after all they had given up a well-paying job to go back to school.
On the research side, well, there we were all equal - we all had to learn what it was about, how to do it, and actually get things done. We all struggled at the beginning, even the experienced engineers. Doing PhD research is not doing a regular engineering job.
I will say, aside a few outliers, the experienced folks graduated a bit earlier. This mainly goes back to them knowing why they were in grad school. Particularly those with families focused more on getting to the end versus enjoying the ride so to speak. For example, I knew one student (married, 4 kids) who went home at 5pm every day to have the evening with their family. After the kids went to bed he went and sat in his car in the apartment parking lot to do more work. That way he didn't waste time driving back to the lab, didn't bother the kids trying to sleep, and was close by if there were any issues needing another parent.
Over the years I've hired a number of folks with PhDs or Masters to work in a national lab. Some went straight through, some didn't. I can't say that either experience makes a difference in how they came up to speed on the research requirements. About the only differentiating factor is those with real work experience are initially better at interacting with everyone across all positions. By that I mean working well with the techs and other support staff to get more done. Any difference there does not last long.
So, congratulations, you currently have a good relationship with your advisor. Don't screw it up. Your advisor is likely happy to have somebody with a proven track work of being able to work. But this work (PhD research) is different, and you will have to show you can actually do it.
As an aside, the other students have much to bring to the table as well - you will all struggle at times and the support they can give you (and you give them) will be invaluable. So, don't screw that up either.