It is surely not. But there are some similitudes and some common principles.
Ethical leadership is leadership that is directed by respect for ethical beliefs and values of others and for the dignity and rights of others. It is thus related to concepts such as trust, honesty, consideration, charisma fairness etc.
Spiritual leadership involves intrinsically motivating and inspiring workers through hope/faith in a vision of service to key stakeholders and a corporate culture based on the values of altruistic love to produce a highly motivated, committed and productive workforce. The purpose of spiritual leadership is to tap into the fundamental needs of both leaders and followers for spiritual well-being through calling (life has meaning and makes a difference) and membership (belonging); to create vision and value congruence across the individual, empowered team, and organization levels; and, ultimately, to foster higher levels of employee well-being, organizational commitment, financial performance, and social responsibility – the Triple Bottom Line
Off the top of my head, spiritual leadership is leadership within a spiritual organization or in a spiritual context. Ethical leadership could be leadership in any context where the practitioner is operating within ethical considerations.
To be an ethical leader doesn´t mean you are a spiritual leader. Being a spiritual leader involves your ethical values. Spiritual leadership starts with spritual inteligence which means your thriving for purpose and meaning and for the good. Employees who are guided through a leader with both spiritual and emotional intelligence will probably experience well-being while working together and at the same time contribute to the "bottom line". So thriving to become a spiritual leader is to recommend. Important though is that spiritual leader is not the same as a religious leader.
A question like this is bound to generate guru style nonsensical replies.
I like Anubhav Singh's response. In my view ethical leadership is one distinct part of spiritual leadership, which we refer to as "Transpersonal Leadership" - leading beyond the ego - because in the West at least, Spiritual can be inferred as meaning religious of mystical and hence confusing the concept. See attached publication (A white paper published by Routledge) for more details.
Article Ethical Leadership: How to develop ethical leaders
Anubhav's descriptions reflect the theoretical distinctions in the literature. If you talk to employees who are engaged in prosocial behaviour/CSR, in practice, and probe their motivations, you will find that spiritual & ethical overlap considerably. I would argue that SL is super-charged EL. Also that SL is motivated by religious as well as non-religious personal values. Using Anubhav's description, then SL sounds more committed, because it is driven by deeply held, personal values.
So what about responsible leadership, then? Voegtlin (in ' What does it mean to be responsible? Addressing the missing responsibility dimension in ethical leadership research, in the journal called 'Leadership', 2016) identified four dimensions of responsibility: '(1) the leader is not isolated as the sole agent of responsibility, (2) the leader has the ability to critically evaluate the prevailing norms and rules, (3) leadership is forward-looking, and (4) leadership is shared and involves collective problem-solving.' (P.27). He concluded that further research 'could theorize further on the interrelation between ethics and responsibility, by examining, for example, whether leaders can be ethical without being responsible or vice versa.' P. 33
I agree with Anubhav's observation that respect and love for others (I include the environment as 'other', it is a stakeholder too) is the key. This is the ethos of stakeholder management. So you might be going through the motions and ticking the boxes, which is ethical. But it's just the starting point. See Freeman and Auster's book 'Bridging the Values Gap: How Authentic organizations Bring Values to Life' (2015) re how to do it.
In regards to leadership development, my project found attentiveness to ones spiritual development accelerates the growth in ethics.
Leadership Development: A Means to Authenticity
Leadership Development: A Means to Authenticity validates the importance of personal and spiritual growth in leadership development as a foundation for ethical, healthy, and productive work, relationships, and community life. The empirical research of this project was mostly conducted at Ireland Cancer Center, University Hospitals.