Youth vacation
If you are younger than 25 and have just graduated, you are entitled to a youth vacation. You get this right if you have worked for at least one month in the year you graduated. This employment can be a month in a row, but also a month spread over different jobs. You will then receive a maximum of four weeks of holiday the following year, minus the number of vacation days to which you are entitled under the normal holiday scheme. Those are the days that you have built up by working at least that one month. In the end you will have a nice jar of vacation days that you can enjoy.
Please note that youth holidays are a right, but not an obligation. An employer must therefore agree to this first. Moreover, you do not get the youth holiday just like that. There are some steps you need to take first, and documents that you need to fill out.
All information about this can be found here.
Additional leave (European holidays)
Additional leave is like youth vacation, but is broader. Age is not taken into account here. You get additional vacation if you have no or few vacation rights accrued in the previous year. This may be the case if you have just graduated, have not worked for a long time, or have only worked for a limited time.
In addition, in order to be entitled to additional holiday, you must first complete a start-up period of three months (or 90 calendar days). If you have used up all your 'normal' vacation days, you can take additional vacation. Again, this is only possible with the permission of your employer.
All information about additional holidays can be found here.