I think Sir William and Mr. Collins have different dispositions and in spite of some similarities they are rather different kind of men. There are probably other examples but this is what jumps out at me first.

Neither is a shining example of intellect:

Sir William Lucas, and his daughter Maria, a good-humoured girl, but as empty-headed as himself… (Ch. 27)

Mr. Collins was not a sensible man, and the deficiency of nature had been but little assisted by education or society… (Ch. 15)

Each is a relentless talker:

[Sir William & Maria] had nothing to say that could be worth hearing, and were listened to with about as much delight as the rattle of the chaise. Elizabeth loved absurdities, but she had known Sir William's too long. He could tell her nothing new of the wonders of his presentation and knighthood; and his civilities were worn out, like his information. (Ch. 27)

Mr. Collins was to attend them, at the request of Mr. Bennet, who was most anxious to get rid of him, and have his library to himself; for thither Mr. Collins had followed him after breakfast, and there he would continue, nominally engaged with one of the largest folios in the collection, but really talking to Mr. Bennet, with little cessation, of his house and garden at Hunsford. (Ch. 15)

They are both are somewhat full of themselves:

Sir William Lucas had been formerly in trade in Meryton… and risen to the honour of knighthood… The distinction had perhaps been felt too strongly. It had given him a disgust to his business, and to his residence in a small market town… (Ch. 5)

The subjection in which his [Mr. Collin’s] father had brought him up had given him originally great humility of manner; but it was now a good deal counteracted by the self-conceit of a weak head, living in retirement, and the consequential feelings of early and unexpected prosperity. (Ch. 15)

They both have a rather substantial (and amusing) deference for rank:

Sir William, to Elizabeth's high diversion, was stationed in the doorway, in earnest contemplation of the greatness before him, and constantly bowing whenever Miss De Bourgh looked that way… (Ch. 28).

Mr. Collins was walking the whole morning within view of the lodges opening into Hunsford Lane, in order to have the earliest assurance of it; and after making his bow as the carriage turned into the Park, hurried home with the great intelligence. (Ch. 30)

Although both men appear to be extremely courteous and attentive to others with Mr. Collins I think it is usually little more than affectation. There is no generous spirit behind his civilities—even his bliss, Lady Catherine, is subject to his prearranged “little elegant compliments as may be adapted to ordinary occasions” and I cannot think of an action that is not tainted by self-interest. His “plan of amends -- of atonement -- for inheriting their father's estate” was always conditional on self-interest:

“Having now a good house and very sufficient income, he intended to marry; and in seeking a reconciliation with the Longbourn family he had a wife in view, as he meant to chuse one of the daughters, if he found them as handsome and amiable as they were represented by common report. This was his plan of amends -- of atonement -- for inheriting their father's estate; and he thought it an excellent one, full of eligibility and suitableness, and excessively generous and disinterested on his own part.” (Ch. 15)

On the other hand Sir William does appear to have a sincere interest in making people comfortable with his courtesies although I grant he can be rather silly and annoying in his efforts as well as unsuccessful as when he tried to get Lizzy & Darcy together for a dance in Ch. 6. The narrator does attest to the good motives behind his civilities:

…denominated from that period Lucas Lodge, where he could think with pleasure of his own importance, and, unshackled by business, occupy himself solely in being civil to all the world. For, though elated by his rank, it did not render him supercilious; on the contrary, he was all attention to everybody. By nature inoffensive, friendly, and obliging, his presentation at St. James's had made him courteous. (Ch. 5)