JBroadway said: "Regarding Bobby/Bobbi - I think some of the confusion here is that "belting" is not actually a technical term, and we don't generally use the term "belter" to describe Tenor/Baritone roles. Because unless you have a countertenor type role that uses a lot of head voice (which is somewhat rare in musical theatre), tenors are generally expected to be singing in their chest voices most of the time. And so they're probably "belting" anytime they sing a high note, but don't think of it as belting, we just think of it as singing high in your chest voice. I feel like we hear "belter" described for women more often, to distinguish from sopranos or mixers who use their head voice more regularly.
If you look at Bobby's highest notes in Company, he's almost always singing it in his chest voice, aka "belting" if you want to use that term. I believe he goes up to G# - not THAT high for a true tenor, but high for a baritenor, and high enough that when you're singing at full voice, it might sound like high belting depending on the actor.
Lenk, by contrast, has been singing many of her higher notes in her head voice. And it sounds like the higher songs straddle her passaggio, which is what makes it sound weak by comparison. The sad thing is that she sounds fantastic when the notes fall on her higher-chest voice range - I wish they had just lowered the keys for her, and nobody would be complaining about her voice sounding weak.
For the record, I thought her performance as Bobbi was fantastic."
That’s very much dependant on where and with what technique you have been friend. Estil is the technique taught most widely to musical theatre singers, in Europe and belting is very much a technical term. Belting being literally shouting on pitch (the way a baby does, with no tension in the body) it involves breathing high and not supporting from the diaphragm. It’s not something that you generally hear for an entire song because it’s a fairly metallic and unsubtle sound, its straight with no vibrato (Idina Mendel true belts in the European sense. Hence you can hear the high snatched breaths) most people tilt their larynx and mix belt with twang - if someone has vibrato that’s a mix, not true belt. Ethel Merman also has many moments of true belt but also natural mixes because you then also get the vibrato.
So whilst the previous poster is right, it’s very much dependant on how you’ve been trained. There are plenty of singers on Broadway who subscribe to the method above.