In a Nutshell:Sovereignty
Islamic states are underpinned by immutable laws based on Quran and Sunnah, the caliph is chosen by the people for life. The caliph appoints the hierarchy of governance, with the ultimate aim of ensuring justice and prosperity for all humanity so they can collectively serve God. Secular democracy marginalises the divine from rule, claims the majority decide on governance, which in reality tend to be subservient to economic interests.
An Islamic State is based upon sovereignty to the Creator, who doesn't change his mind, is not prone to prejudice, bigotry or ignorance.
A Western secular democracy is based upon sovereignty of the Individual, who does change their mind, is prone to prejudice, bigotry and ignorance. Divine or Secular Legislation
In an Islamic state the ruler is elected based upon confidence to lead. He is obliged to derive laws based upon Qur'an and Sunnah having no option to ignore the clear laws contained therein, even if it inconveniences government. It in turn always provides full protections for people's needs.
In a Western secular democracy, leaders are not required to consult the people in running their affairs nor fulfil their promises. They derive laws from what is convenient and may and often take away people's rights using that justification. The leader remains in power despite being unjust or incompetent and may get elected again if he can lie to the people to persuade them he is the lesser of two evils. Rule for Life or Transitory
In an Islamic State, the leader's position is secure and can't be bullied, controlled or bossed around by corporations, lobby groups and rich businessmen - and so remains independent to pursue his conscience.
In a Western secular democracy, the leader is dependent on money from corporations, lobby groups and rich businessmen, to fund his re-election campaigns and fund his party. Security
An Islamic state protects rights, even when it's not convenient.
A Western secular democracy gives you your rights, until it's not convenient. Consultation
Islam demands rulers seek your opinion and not make false promises and lies to get your vote every four years.
In a Western secular democracy, the leaders seek your vote, not your opinion.
In 1786 the French Ambassador in Istanbul, Count de Choiseul-Gouffier, wrote a letter back to King Louis XVI expressing frustration at waiting upon decisions from the Ottoman Caliphs, because he didn't dictate decisions like European Kings did:
"Here things are not as in France where the king is sole master and does as he pleases. Here the sultan has to consult. He has to consult with the former holders of high offices, with the leaders of various groups and so on. And this is a slow process."Conclusion
Islamic states are quite distinct from secular states. They are underpinned by immutable laws based on scripture, the caliph is chosen by the people and his office is for life. He in turn appoints the hierarchy of governance, with the ultimate aim of ensuring justice and prosperity for all humanity so they can collectively serve God. Secular democracy marginalises the divine from rule, claims the majority decide on governance, which in reality tend to be subservient to economic interests, with an aim of allowing people to achieve "happiness" however they see fit.