IUIT (iShares S&P 500 Information Technology Sector UCITS ETF USD) vs EQQQ (Invesco EQQQ NASDAQ-100 UCITS ETF)

Hi, is anyone able to find the difference between the 2 tech ETFs?
I already know they track 2 different indexes (S&P 500 Information Technology Sector for IUIT and Nasdaq 100 for EQQQ), so maybe my question would be: which is the difference between the indexes?

IUIT sector breakdown:

Systems Software 22.56
TECHNOLOGY HARDWARE, STORAGE & PERIPHERALS 18.79
Data Processing & Outsourced Services 17.29
Semiconductors 16.66
Application Software 8.21
IT Consulting & Other Services 5.90
Communications Equip. 5.72
Semiconductor Equipment 1.77
Electronic Components 1.03
Electronic Manufacturing Services 0.73
Internet Services & Infrastructure 0.64

EQQQ:

Information Technology 44.74%
Communication Services 21.97%
Consumer Discretionary 16.77%
Health Care 7.67%
Consumer Staples 5.78%
Industrials 2.44%
Utilities 0.35%
Financials 0.28%

As you can see the sectors are different so no comparison possible.

As regards the first 10 actual holdings:

IUIT:

MICROSOFT CORP 18.77
APPLE INC 16.84
VISA INC CLASS A 5.39
CISCO SYSTEMS INC 4.61
INTEL CORP 4.30
MASTERCARD INC CLASS A 4.30
ADOBE INC 2.64
ORACLE CORP 2.64
PAYPAL HOLDINGS INC 2.48
SALESFORCE.COM INC 2.37

EQQQ:

Microsoft 10.75
Amazon 10.16
Apple 10.16
Facebook ‘A’ 5.00
Alphabet ‘C’ 4.49
Alphabet ‘A’ 3.96
Cisco Systems 2.93
Intel 2.73
Comcast ‘A’ 2.34
PepsiCo 2.14

So there is a difference, but how can it be described by the index selection rules?

S&P500 Information technology sounds like a sector-specific subset of S&P500:

while NASDAQ100 is an exchange-specific multi-sector index with a sector-specific exclusion:

Thank you, reading your links I found a main difference: Nasdaq100: no financials!

NASDAQ100 contains all the FAANGS, including Netflix (look at the comprehensive 100 list and Netflix is about 14th), IT doesn’t

The sectors got redistributed last year or so and everything got jumbled up. So if your looking for the FAANGS, NASDAQ100 was the only choice.

NASDAQ100 top holdings are mainly IT, but there are some others like pharma. But it is 50% by weight FAANG