Trumpet and Flugelhorn differences/similarities

The flugelhorn sound is warmer, darker and more mellow (less brassy and not as penetrating) as the trumpet. Like the trumpet and cornet, it has 3 valves and the fingering is the same. Most are in B flat, though some are in C.

In terms of going from brassy to mellow the order is trumpet, cornet, flugelhorn.

The flugelhorn and cornet are a nice blend connecttion between french horns and trumpets and many late romantics exploited this characteristic of the cornet. (Unfortunately there are many recordings of those 19th C scores which substitute trumpets for the cornet parts.) Berlioz and French composers used the cornet often, as did Tchaikovsky in several orchestral scores (Capriccio Italien, Francesca da Rimini, etc) and operas. (Don't recall off hand flugelhorn usage.) But...

I use the soundfont "Symphonic Sounds". There are several trumpet fonts therein and one flugelhorn font. In a large orchestra my scores call for 2 trumpets and 2 cornets. As there is no cornet sound in the font, I substitute the flugelhorn sound with somewhat satisfactory results.

For more technical info and physical description: https://bandestration.com/2015/10/22/trumpet-vs-cornet-vs-flugelhorn/

Hope this helps
Joe

Should be easy enough to find videos/recordings online to help you hear the difference. FWIW, those in my generation mostly were introduced to the flugelhorn by Chuck Mangione, who had a pop hit "Feels So Good" back in 1970's.

Also, as a practical consideration, while technically the ranges of the instruments should be the same, the flugelhorn tends to be be played lower. That is, notes below middle C that sound kind of "flabby" on the trumpet sound much nicer on flugel, notes above high C that jazz trumpet players often use to good (or sometimes not so good!) effect are less effective and I guess harder to play as well.