Issue with responsive optimization at mobile devices / urgent customer project

Hello;
I have got some trouble with the responsive optimization at the following devices:
– Tablet (portrait)
– Smartphone (landscape)
– Smartphone (portrait)

I have optimized my site for tablet (portait) so the smartphone (portrait) looks good, too.
But the smartphone (landscape) looks ugly.

And when I optimize smartphone (landscape), then smartphone (portrait) and tablet (portait) looks ugly.

It seems that there is no case distinction between the two groups:
– smartphone (portrait) and tablet (portrait)
– smartphone (landscape)

So I can’t reach a good solution for all these 3 devices.

How to distinguish this 2 groups of devices???

Please, I need help to solve this for an urgent customer project.

kind regards,
Bernhard