14 or 15.6 laptop with the same equipment?

I'm almost desperate because I can't decide between a 14 and a 15.6 incher.
To the background:
I've only owned a 15.6 inch laptop that I've used for almost 6 years. I'm a student and occasionally take my laptop with me and also in the library when I'm learning / working there. But so far I have only taken it if it had to be sure, since my laptop weighs quite a lot and not exactly agile comes → 3,3cm height x 38,2cm width x 25,3cm depth at 2.6kg
Of course, it is comparatively clumsy to today's 15.6 "and meanwhile you can easily find a 15 incher with 1.8kg, with comparatively much more compact dimensions with narrower screen margins.
The display size in itself, I appreciate very much, I like to work with the (split-screen) and me to watch videos on it.
Therefore, I'm currently very indecisive, if I would like the "downgrade" to a 14 inches.
Specifically, it is about two laptops that are almost the same equipped with the difference that the 14 incher has a double SSD and is also 20 euro cheaper.
Price-performance-wise, I find the offer for the 14 "laptop better, but I'm not sure if I would come with the display size.
Because I'm used to a 15.6 "for a very long time.
But I could imagine him taking more with the 14 "as he is a bit more compact and 300gr lighter than his 15.6" counterpart.

Conclusion:
I'm very undecided which is the right choice for me and would like to hear your tips especially from people who have switched from a 15.6 "to a 14"!

Thank you for your attention and best regards.

edit:
Both have a FHD screen (1920 x 1080) and have a matte IPS panel.
My current laptop has a glossy display with 1366 x 768 pixels.

Order 14 inches, you have 14 days return policy.

or

At Mediamarkt look if that is such a huge difference

As long as the resolution is the same, it is incidentally 14 inches or 15.6 inches. Is then only correspondingly smaller but the space for Splitscreen etc remains the same.

Stay at 15.6. The price difference is only small. Besides, you are already used to working with one of these sizes. I once made the mistake and bought a netbook. 10 ". That was a big difference, there was nothing to write with 10Finger.

That will not be so blatant here.

Maybe you just go to a Saturn oä and look at devices of this size. Then you can compare directly?

A netbook is a pocket calculator, but with 14 inch models I have the best experience. They usually have a much better keyboard layout than the 15 inch models, because the useless numeric keypad is missing and the much more important typing keys do not have to be bunched together - that's a mess for me, nothing more.

I have both a 15.6 "and a 14". I always take the newer 14-inch model on the road and find it pleasant that it is smaller, lighter and more stable. The 15.6 "stays at home and is the more commonly used for surfing etc.

If the 15.6 "were broken, I would instead only get a larger monitor and operate it with the smaller one.

Important to me is the keyboard, if you write a lot, it should be the most important criterion. The 15.6 "are unfortunately barely obtainable without a number pad, so the keys are narrower and the letter block is no longer centered on the screen, which can even lead to tension.