Because the idea that both of these are simply caused by microorganisms is wrong.        

   Tonsillitis is is probably a result of maladjustment of developmental lymphatic drainage from the head, providing niches for bugs to thrive.  

     I have no idea what causes quinsy, but the presence of bugs is surely an epiphenomenon since it is often unilateral.  This suggests some localised mechanical or traumatic damage.

    I never had tonsillitis as a child, but had quinsy in middle age.

Abstract

OBJECTIVE:

To review the literature concerning the 2 primary hypotheses put forth to explain the pathogenesis of peritonsillar abscess: "the acute tonsillitis hypothesis" (peritonsillar abscess is a complication of acute tonsillitis) and "the Weber gland hypothesis" (peritonsillar abscess is an infection of Weber's glands).

DATA SOURCES:

PubMed, EMBASE.

REVIEW METHODS:

Data supporting or negating one hypothesis or the other were elicited from the literature.

CONCLUSIONS:

Several findings support the acute tonsillitis hypothesis. First, the 2 main pathogens in peritonsillar abscess have been recovered from pus aspirates and bilateral tonsillar tissues with high concordance rates, suggesting that both tonsils are infected in patients with peritonsillar abscess. Second, studies report signs of acute tonsillitis in the days prior to and at the time of peritonsillar abscess. Third, antibiotic treatment reduces the risk of abscess development in patients with acute tonsillitis. However, some findings suggest involvement of the Weber's glands in peritonsillar abscess pathogenesis. First, high amylase levels have been found in peritonsillar pus. Second, the majority of peritonsillar abscesses are located at the superior tonsillar pole in proximity of the Weber's glands. We propose a unified hypothesis whereby bacteria initially infect the tonsillar mucosa and spread via the salivary duct system to the peritonsillar space, where an abscess is formed.

IMPLICATIONS FOR PRACTICE:

Our findings support the rationale for antibiotic treatment of patients with severe acute tonsillitis to reduce the risk of abscess development. Improved understanding of peritonsillar abscess pathogenesis is important for the development of efficient prevention strategies.

© American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016

1: Klug TE, Rusan M, Fuursted K, Ovesen T. Peritonsillar Abscess: Complication of

Acute Tonsillitis or Weber's Glands Infection? Otolaryngol Head Neck Surg. 2016

Aug;155(2):199-207. doi: 10.1177/0194599816639551. Epub 2016 Mar 29. Review.

PubMed PMID: 27026737.

Kindly go through this information. 

Is there any change in these Weber's glands with age ? 

"We propose a unified hypothesis whereby bacteria initially infect the tonsillar mucosa and spread via the salivary duct system to the peritonsillar space, where an abscess is formed."

This theory falls at the first hurdle since it cannot explain a unilateral abscess. 

But most of the patients we see do have acute tonsillitis prior to quinsy which was untreated or inadequately treated. 

I don't know how to explain- 1. the reason for quinsy occurring in the young age group

                                              2. why is it unilateral in almost all cases 

"But most of the patients we see do have acute tonsillitis prior to quinsy which was untreated or inadequately treated."

I do not understand this point.    Clearly there is infection in quinsy, and it has to come from somewhere.

I never had tonsillitis before I had quinsy, for which an operation was recommended. 

Sir did you undergo quinsy drainage?  Was pus aspirated from the same ? 

"Sir did you undergo quinsy drainage?"

My tonsils were shown to all and sundry in the ENT dept.   I declined the kind offer of surgery, and the quinsy soon cleared up.   I was warned that this would mean that the problem was likely to recur, and in fact I do now have occasional bad colds starting with a sore throat, but I think I probably made the right decision .   

A well formed peritonsillar abscess - quinsy  is different from early peritonsillar inflammation. Abscess requires intervention with iv antibiotics/ aspiration or drainage. 

Most cases who have this come with high fever, decreased and painful mouth opening and require hospitalization. 

"Most cases who have this come with high fever, decreased and painful mouth opening and require hospitalization."

I cannot remember if I had a fever, but it was very painful and I was advised to go onto the ward immediately.   I discharged myself against medical advice! 

It is obvious observation, for me I don’t know  why quinsy affects adults more than children despite acute tonsillitis is more in children. Also I don’t know why quinsy is mostly unilateral while acute tonsillitis is bilateral. Moreover if you remember I asked a question why during tonsillectomy sometime we found debris is drained from only one tonsil in spite of chronic infection affects both tonsils.